Low Mass Group Environments have no Substantial Impact on the Circumgalactic Medium Metallicity

We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low mass galaxy groups (2-5 galaxies) at $\langle z_{abs}\rangle=0.25$ identified near background quasars. Using quasar spectra from HST/COS and from Keck/HIRES or VLT/UVES we measure column densities of, or determine limits on, CGM absorption lines. We use a Markov chain Monte Carlo approach with Cloudy to estimate metallicities of cool ($T\sim10^4$K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range ($-2<$[Si/H]$<0$), where the mean group ($-0.54\pm0.22$) and isolated ($-0.77\pm0.14$) CGM metallicities are similar. Group and isolated environments have similar distributions of {\HI} column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anti-correlation between {\HI} column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging, or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.Comment: 14 pages, 5 figures, 2 figure sets, 1 machine-readable tabl

The Relation Between Galaxy ISM and Circumgalactic OVI Gas Kinematics Derived from Observations and Λ\LambdaCDM Simulations

We present the first galaxy-OVI absorption kinematic study for 20 absorption systems (EW>0.1~{\AA}) associated with isolated galaxies (0.15$<z<$0.55) that have accurate redshifts and rotation curves obtained using Keck/ESI. Our sample is split into two azimuthal angle bins: major axis ($\Phi<25^{\circ}$) and minor axis ($\Phi>33^{\circ}$). OVI absorption along the galaxy major axis is not correlated with galaxy rotation kinematics, with only 1/10 systems that could be explained with rotation/accretion models. This is in contrast to co-rotation commonly observed for MgII absorption. OVI along the minor axis could be modeled by accelerating outflows but only for small opening angles, while the majority of the OVI is decelerating. Along both axes, stacked OVI profiles reside at the galaxy systemic velocity with the absorption kinematics spanning the entire dynamical range of their galaxies. The OVI found in AMR cosmological simulations exists within filaments and in halos of ~50 kpc surrounding galaxies. Simulations show that major axis OVI gas inflows along filaments and decelerates as it approaches the galaxy while increasing in its level of co-rotation. Minor axis outflows in the simulations are effective within 50-75 kpc beyond that they decelerate and fall back onto the galaxy. Although the simulations show clear OVI kinematic signatures they are not directly comparable to observations. When we compare kinematic signatures integrated through the entire simulated galaxy halo we find that these signatures are washed out due to full velocity distribution of OVI throughout the halo. We conclude that OVI alone does not serve as a useful kinematic indicator of gas accretion, outflows or star-formation and likely best probes the halo virial temperature.Comment: 24 pages, 21 figures, 4 tables. Accepted to ApJ on November 14, 201

'Mindless markers of the nation': The routine flagging of nationhood across the visual environment

The visual environment has increasingly been used as a lens with which to understand wider processes of social and economic change with studies employing in-depth qualitative approaches to focus on, for example, gentrification or trans-national networks. This exploratory paper offers an alternative perspective by using a novel method, quantitative photo mapping, to examine the extent to which a particular socio-cultural marker, the nation, is ‘flagged’ across three contrasting sites in Britain. As a multi-national state with an increasingly diverse population, Britain offers a particularly fruitful case study, drawing in debates around devolution, European integration and Commonwealth migration. In contributing to wider debates around banal nationalism, the paper notes the extent to which nations are increasingly articulated through commerce, consumption and market exchange and the overall significance of everyday markers (signs, objects, infrastructure) in naturalising a national view of the world

The Relationship Between Galaxy ISM and Circumgalactic Gas Metallicities

We present ISM and CGM metallicities for 25 absorption systems associated with isolated star-forming galaxies (=0.28) with 9.4<log(M*/Msun)<10.9 and with absorption detected within 200kpc. Galaxy ISM metallicities were measured using Ha/[NII] emission lines from Keck/ESI spectra. CGM single-phase low-ionization metallicities were modeled using MCMC and Cloudy analysis of absorption from HST/COS and Keck/HIRES or VLT/UVES quasar spectra. We find that the star-forming galaxy ISM metallicities follow the observed stellar mass metallicity relation (scatter 0.19dex). CGM metallicity shows no dependence with stellar mass and exhibits a scatter of ~2dex. All CGM metallicities are lower than the galaxy ISM metallicities and are offset by log(dZ)=-1.17+/-0.11. There is no obvious metallicity gradient as a function of impact parameter or virial radius (<2.3 sigma). There is no relationship between the relative CGM-galaxy metallicity and azimuthal angle. We find the mean metallicity differences along the major and minor axes are -1.13+/-0.18 and -1.23+/-0.11, respectively. Regardless of whether we examine our sample by low/high inclination or low/high impact parameter, or low/high N(HI), we do not find any significant relationship with relative CGM-galaxy metallicity and azimuthal angle. We find that 10/15 low column density systems (logN(HI)<17.2) reside along the galaxy major axis while high column density systems (logN(HI)>17.2) reside along the minor axis. This suggest N(HI) could be a useful indicator of accretion/outflows. We conclude that CGM is not well mixed, given the range of galaxy-CGM metallicities, and that metallicity at low redshift might not be a good tracer of CGM processes. Furthermore we should replace integrated line-of-sight, single phase, metallicities with multi-phase, cloud-cloud metallicities, which could be more indicative of the physical processes within the CGM.Comment: 10 pages, 6 figures, 1 table. Accepted to ApJ on October 7, 201

Paediatric tube-feeding: An agenda for care improvement and research.

This article presents an agenda to improve the care and wellbeing of children with paediatric feeding disorder who require tube feeding (PFD-T). PFD-T requires urgent attention in practice and research. Priorities include: routine collection of PFD-T data in health-care records; addressing the tube-feeding lifecycle; and reducing the severity and duration of disruption caused by PFD-T where possible. This work should be underpinned by principles of involving, respecting and connecting families

Relationship between the Metallicity of the Circumgalactic Medium and Galaxy Orientation

We investigate the geometric distribution of gas metallicities in the circumgalactic medium (CGM) around $47$, $z<0.7$ galaxies from the "Multiphase Galaxy Halos" Survey. Using a combination of quasar spectra from HST/COS and from Keck/HIRES or VLT/UVES we measure column densities of, or determine limits on, CGM absorption lines. We then use a Monte-Carlo Markov chain approach with Cloudy to estimate the metallicity of cool (T$\sim$$10^4$K) CGM gas. We also use HST images to determine host galaxy inclination and quasar--galaxy azimuthal angles. Our sample spans a HI column density range of $13.8$ cm s$^{-1}<{\log N_{HI}}<19.9$ cm s$^{-1}$. We find (1) while the metallicity distribution appears bimodal, a Hartigan dip test cannot rule out a unimodal distribution ($0.4\sigma$). (2) CGM metallicities are independent of halo mass, spanning three orders of magnitude at fixed halo mass. (3) The CGM metallicity does not depend on the galaxy azimuthal and inclination angles regardless of HI column density, impact parameter and galaxy color. (4) Ionization parameter does not depend on azimuthal angle. We suggest that the partial Lyman limit metallicity bimodality is not driven by a spatial azimuthal bimodality. Our results are consistent with simulations where the CGM is complex and outflowing, accreting, and recycled gas are well-homogenized at $z<0.7$. The presence of low metallicity gas at all orientations suggests that cold streams of accreting filaments are not necessarily aligned with the galaxy plane at low redshifts or intergalactic transfer may dominate. Finally, our results support simulations showing that strong metal absorption can mask the presence of low metallicity gas in integrated line-of-sight CGM metallicities.Comment: 87 pages, 22 pages of main text, 65 pages of appendices, 106 figures and 50 tables. Accepted for publication in ApJ 31 July 201

´Waste-to-energy' fuel cell systems

Funding: Defence Science and Technology Lab.In this paper, a review of the different possible gas and solid fuels for solid oxide fuel cells (SOFCs) is presented. Much research has been performed with gaseous fuels in SOFCs. On the contrary, much work remains on the direct use of solid fuels in SOFCs to overcome all the technical challenges that these systems present. The challenges are even greater when the use of complex solid waste is considered. However, the development of efficient and sustainable energy systems that can operate with waste is of general interest to the energy sector and the environment, as waste management is of major concern. In particular, the re-utilisation or disposal of plastics is of great importance due to their worldwide usage and their slow degradation. The use of an untreated wood and polystyrene mixture in an electrolyte-supported fuel cell with a NiO-YSZ anode and LSM-based cathode was also investigated in this work.Postprin