Do we (mis)recognise the political power of Twitter?

We are told that Twitter is the new public sphere, the place where we hold government accountable, encourage diverse voices, and provide resources for public benefit like education, healthcare, and welfare. Using the #metoo campaign as a case study, Naomi Barnes and Huw Davies question whether Twitter really is a public sphere or if it is simply a platform capitalist that monetises displays of outrage

Tidal Limits to Planetary Habitability

The habitable zones of main sequence stars have traditionally been defined as the range of orbits that intercept the appropriate amount of stellar flux to permit surface water on a planet. Terrestrial exoplanets discovered to orbit M stars in these zones, which are close-in due to decreased stellar luminosity, may also undergo significant tidal heating. Tidal heating may span a wide range for terrestrial exoplanets and may significantly affect conditions near the surface. For example, if heating rates on an exoplanet are near or greater than that on Io (where tides drive volcanism that resurface the planet at least every 1 Myr) and produce similar surface conditions, then the development of life seems unlikely. On the other hand, if the tidal heating rate is less than the minimum to initiate plate tectonics, then CO_2 may not be recycled through subduction, leading to a runaway greenhouse that sterilizes the planet. These two cases represent potential boundaries to habitability and are presented along with the range of the traditional habitable zone for main sequence, low-mass stars. We propose a revised habitable zone that incorporates both stellar insolation and tidal heating. We apply these criteria to GJ 581 d and find that it is in the traditional habitable zone, but its tidal heating alone may be insufficient for plate tectonics.Comment: 13 pages, 2 figures, accepted to ApJ Letters. A version with full resolution images is available at http://www.astro.washington.edu/users/rory/publications/bjgr09.pd

Anoxic nitrification in marine sediments

Nitrate peaks are found in pore-water profiles in marine sediments at depths considerably below the conventional zone of oxic nitrification. These have been interpreted to represent nonsteady- state effects produced by the activity of nitrifying bacteria, and suggest that nitrification occurs throughout the anoxic sediment region. In this study, ΣNO3 peaks and molecular analysis of DNA and RNA extracted from anoxic sediments of Loch Duich, an organic-rich marine fjord, are consistent with nitrification occurring in the anoxic zone. Analysis of ammonia oxidiser 16S rRNA gene fragments amplified from sediment DNA indicated the abundance of autotrophic ammonia-oxidising bacteria throughout the sediment depth sampled (40 cm), while RT-PCR analysis indicated their potential activity throughout this region. A large non-steady-state pore-water ΣNO3 peak at ~21 cm correlated with discontinuities in this ammonia-oxidiser community. In addition, a subsurface nitrate peak at ~8 cm below the oxygen penetration depth, correlated with the depth of a peak in nitrification rate, assessed by transformation of 15N-labelled ammonia. The source of the oxidant required to support nitrification within the anoxic region is uncertain. It is suggested that rapid recycling of N is occurring, based on a coupled reaction involving Mn oxides (or possibly highly labile Fe oxides) buried during small-scale slumping events. However, to fully investigate this coupling, advances in the capability of high-resolution pore-water techniques are required

The Arecibo Galaxy Environment Survey V : The Virgo Cluster (I)

We present 21 cm observations of a 10 $\times$ 2 degree region in the Virgo cluster, obtained as part of the Arecibo Galaxy Environment Survey. 289 sources are detected over the full redshift range (-2,000 $<$ $v$$_{hel}$ $<$ + 20,000 km/s) with 95 belonging to the cluster ($v$$_{hel}$ $<$ 3,000 km/s). We combine our observations with data from the optically selected Virgo Cluster Catalogue (VCC) and the Sloan Digital Sky Survey (SDSS). Most of our detections can be clearly associated with a unique optical counterpart, and 30% of the cluster detections are new objects fainter than the VCC optical completeness limit. 7 detections may have no optical counterpart and we discuss the possible origins of these objects. 7 detections appear associated with early-type galaxies. We perform HI stacking on the HI-undetected galaxies listed in the VCC in this region and show that they must have significantly less gas than those actually detected in HI. Galaxies undetected in HI in the cluster appear to be really devoid of gas, in contrast to a sample of field galaxies from ALFALFA.Comment: 23 pages, 22 figures, 4 table

L1 and off Sun-Earth line visible-light imaging of Earth-directed CMEs: An analysis of inconsistent observations

The efficacy of coronal mass ejection (CME) observations as a key input to space weather forecasting is explored by comparing on and off Sun-Earth line observations from the ESA/NASA SOHO and NASA STEREO spacecraft. A comparison is made of CME catalogues based on L1 coronagraph imagery and off Sun-Earth line coronagraph and heliospheric imager (HI) observations, for the year 2011. Analysis reveals inconsistencies in the identification of a number of potentially Earth-directed CMEs. The catalogues reflect our ability to identify and characterise CMEs, so any discrepancies can impact our prediction of Earth-directed CMEs. We show that 15 CMEs, which were observed by STEREO, that had estimated directions compatible with Earth-directed events, had no identified halo/partial halo counterpart listed in the L1 coronagraph CME catalogue. In-situ data confirms that for 9 of these there was a consistent L1 Interplanetary CME (ICME). The number of such "discrepant" events is significant compared to the number of ICMEs recorded at L1 in 2011, stressing the need to address space weather monitoring capabilities, particularly with the inclusion of off Sun-Earth line observation. While the study provides evidence that some halo CMEs are simply not visible in near-Earth coronagraph imagery, there is evidence that some halo CMEs viewed from L1 are compromised by preceding CME remnants or the presence of multiple-CMEs. This underlines (1) the value of multiple vantage point CME observation, and (2) the benefit of off Sun-Earth line platform heliospheric imaging, and coronagraph imaging, for the efficient identification and tracking of Earth-directed events.Comment: 36 pages, 6 figures, in press at AGU Space Weather, 202

About the various contributions in Venus rotation rate and LOD

% context heading (optional) {Thanks to the Venus Express Mission, new data on the properties of Venus could be obtained in particular concerning its rotation.} % aims heading (mandatory) {In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus, and more particularly the angular rotation rate.} % methods heading (mandatory) {Applying models already used for the Earth, the effect of the triaxiality of a rigid Venus on its period of rotation are computed. Then the variations of Venus rotation caused by the elasticity, the atmosphere and the core of the planet are evaluated.} % results heading (mandatory) {Although the largest irregularities of the rotation rate of the Earth at short time scales are caused by its atmosphere and elastic deformations, we show that the Venus ones are dominated by the tidal torque exerted by the Sun on its solid body. Indeed, as Venus has a slow rotation, these effects have a large amplitude of 2 minutes of time (mn). These variations of the rotation rate are larger than the one induced by atmospheric wind variations that can reach 25-50 seconds of time (s), depending on the simulation used. The variations due to the core effects which vary with its size between 3 and 20s are smaller. Compared to these effects, the influence of the elastic deformation cause by the zonal tidal potential is negligible.} % conclusions heading (optional), leave it empty if necessary {As the variations of the rotation of Venus reported here are of the order 3mn peak to peak, they should influence past, present and future observations providing further constraints on the planet internal structure and atmosphere.}Comment: 12 pages, 10 figures, Accepted in A&

Relativistic Quarkonia from Anisotropic Lattices

We report on new results for the spectrum of quarkonia using a fully relativistic approach on anisotropic lattices with quark masses in the range from strange to bottom. A fine temporal discretisation also enables us to resolve excitations high above the ground state. In particular we studied the mass dependence and scaling of hybrid states.Comment: 4 pages, 5 figures. Lattice 2000 (Heavy Quark Physics

Revisiting the De-Radicalisation or Disengagement Debate: Public Attitudes to the Re-Integration of Terrorists

The article reports on the findings of an experimental survey which was conducted to ascertain the level of support and perceived effectiveness of using de-radicalisation programmes to re-integrate returning foreign fighters. Public support (or the lack of opposition) for re-integration programmes can be important in ensuring the programmes have the time, resources and opportunity to be successful however we know little about what wider society thinks about re-integration programmes. The article explores the extent to which the inclusion of de-radicalisation – in name and content – changes attitudes to a re-integration programme. This is relevant in showing attitudes to de-radicalisation over disengagement and whether de-radicalisation, while perhaps not more effective at the programme-level, is or is not more effective at generating public support for re-integration (and thereby facilitating the process itself). We find that the inclusion of de-radicalisation in the name and content of a re-integration programme to a small extent increases support for re-integration over a programme that uses the terms disengagement and desistance. However, we also find that while de-radicalisation increases support, it also decreases perceived effectiveness, leading respondents to feel it makes the country less safe and less likely to reduce the re-offending rate than if the programme excludes de-radicalisation. We argue this polarising effect is reflective of wider reasons for supporting the policies (e.g. de-radicalisation may be seen as a form of ideational/normative punishment) and that the term de-radicalisation may shift the framing of the problematic to entrenched social structures, thus rendering itself ineffective as a policy treatment. In terms of policy, we argue there is a necessity for greater openness about re-integration programmes and that governments would benefit from selling the programmes to the public. We conclude our paper with a justification of focusing further research on understanding public/community attitudes to re-integration programmes and understanding the PR of counter-terrorism policies more generally

Southern GEMS groups II: HI distribution, mass functions and HI deficient galaxies

We investigate the neutral hydrogen (HI) content of sixteen groups for which we have multi-wavelength data including X-ray observations. Wide-field imaging of the groups was obtained with the 20-cm multibeam system on the 64-m Parkes telescope. We have detected ten previously uncatalogued HI sources, one of which has no visible optical counterpart. We examine the HI properties of the groups, compared to their X-ray characteristics, finding that those groups with a higher X-ray temperature and luminosity contain less HI per galaxy. The HI content of a group depends on its morphological make-up, with those groups dominated by early-type galaxies containing the least total HI. We determined the expected HI for the spiral galaxies in the groups, and found that a number of the galaxies were HI deficient. The HI deficient spirals were found both in groups with and without a hot intra-group medium. The HI deficient galaxies were not necessarily found at the centre of the groups, however, we did find that two thirds of HI deficient galaxies were found within about 1 Mpc from the group centre, indicating that the group environment is affecting the gas-loss from these galaxies. We determined the HI mass function for a composite sample of 15 groups, and found that it is significantly flatter than the field HI mass function. We also find a lack of high HI-mass galaxies in groups. One possible cause of this effect is the tidal stripping of HI gas from spiral galaxies as they are pre-processed in groups.Comment: accepted for publication in MNRAS, 26 pages, 13 Figures, 2 Appendice

Towards a novel carbon device for the treatment of sepsis

Sepsis is a systemic inflammatory response to infection in which the balance of pro- andanti-inflammatory mediators, which normally isolate and eliminate infection, is disrupted[1]. Gram negative sepsis is initiated by bacterial endotoxin release which activatesmacrophages and circulating monocytes to release TNF and IL-1β followed by IL-6 andother inflammatory cytokines [2]. As the disease progresses, an unregulatedinflammatory response results in, tissue injury, haematological dysfunction and organdysfunction. Severe sepsis, involving organ hypoperfusion may be further complicatedby hypotension that is unresponsive to adequate fluid replacement, resulting in septicshock and finally death [3].Despite improvements in anti-microbial and supportive therapies, sepsis remains asignificant cause of morbidity and mortality in ICUs worldwide [4]. The complexity ofprocesses mediating the progression of sepsis suggests that an extracorporeal devicecombining blood filtration with adsorption of a wide range of toxins, and inflammatorymediators offers the most comprehensive treatment strategy. However, no such deviceexists at present. A novel, uncoated, polymer pyrolysed synthetic carbon device isproposed which combines the superior adsorption properties of uncoated activatedcarbons with the capacity to manipulate porous structure for controlled adsorption oftarget plasma proteins and polypeptides [5]. Preliminary haemocompatibility andadsorptive capacity was assessed using a carbon matrix prototype