A Far-Infrared Survey of Molecular Cloud Cores

We present a catalogue of molecular cloud cores drawn from high latitude, medium opacity clouds, using the all-sky IRAS Sky Survey Atlas (ISSA) images at 60 and 100~$\mu$m. The typical column densities of the cores are $N(H_2)\sim 3.8 \times 10^{21}$cm$^{-2}$ and the typical volume densities are $n(H_2) \sim 2 \times 10^3$cm$^{-3}$. They are therefore significantly less dense than many other samples obtained in other ways. Those cloud cores with IRAS point sources are seen to be already forming stars, but this is found to be only a small fraction of the total number of cores. The fraction of the cores in the protostellar stage is used to estimate the prestellar timescale - the time until the formation of a hydrostatically supported protostellar object. We argue, on the basis of a comparison with other samples, that a trend exists for the prestellar lifetime of a cloud core to decrease with the mean column density and number density of the core. We compare this with model predictions and show that the data are consistent with star formation regulated by the ionisation fraction.Comment: 13 pages, 7 figure

Brassica cover crops for weed control in organic vegetable production

Cover crops (or green manures) are commonly used by organic vegetable growers for soil fertility building and other benefits including weed control. Brassica crops have been reported to control weeds in subsequent crops, usually attributed to the allelopathic effects of glucosinolates (GSL) in the brassica residues, although the effects are inconsistent. New brassica varieties with high GSL levels (Brassica juncea cv. Fumus and Raphanus sativus cv. Weedcheck) were tested in combination with mechanical weed control and another locally grown forage crop (Lolium multiflorum cv. Conquest) for their effects on weed growth during the pre-crop phase and subsequent weed and lettuce growth during the in-crop phase. The cover crops and bare fallow controlled weeds effectively during the pre-crop phase, but did not affect weed and lettuce growth in the following in-crop phase. The cover crops provided better on-going weed control than the bare fallow. Reducing the delay between the pre- and in-crop phases from four weeks to one day did not affect weed and lettuce growth. Weed control was closely related to the amount of light reduction by the cover crops, while competition for nutrients and water appeared to be less important in weed suppression by the cover crops. The use of cover crops requires careful selection of appropriate varieties, attention to good cover crop husbandry (particularly establishment) and an awareness of prevailing weed seed bank levels

The contested and contingent outcomes of Thatcherism in the UK

The death of Margaret Thatcher in April 2013 sparked a range of discussions and debates about the significance of her period in office and the political project to which she gave her name: Thatcherism. This article argues that Thatcherism is best understood as a symbolically important part of the emergence of first-phase neoliberalism. It engages with contemporary debates about Thatcherism among Marxist commentators and suggests that several apparently divergent positions can help us now reach a more useful analysis of Thatcherism’s short- and long-term outcomes for British political economy. The outcomes identified include: an initial crisis in the neoliberal project in the UK; the transformation of the party political system to be reflective of the politics of neoliberalism, rather than its contestation; long-term attempts at the inculcation of the neoliberal individual; de-industrialisation and financial sector dependence; and a fractured and partially unconscious working class. In all long-term outcomes, the contribution of Thatcherism is best understood as partial and largely negative, in that it cleared the way for a longer-term and more constructive attempt to embed neoliberal political economy. The paper concludes by suggesting that this analysis can inform current debates on the left of British politics about how to oppose and challenge the imposition of neoliberal discipline today

Applying Leventhal's self-regulatory model to pregnancy: Evidence that pregnancy-related beliefs and emotional responses are associated with maternal health outcomes

This study explored whether women’s beliefs about, and emotional responses to, pregnancy could account for variations in maternal mental and physical health outcomes, using the self-regulatory model as a theoretical framework. Women in the last trimester of pregnancy (N = 408) completed an online survey including measures of representations of pregnancy, coping, and physical and mental health. Results revealed that representations of pregnancy accounted for up to 30 and 39 per cent of the variance in indicators of physical and mental health, respectively. Findings suggest that beliefs about pregnancy may have important implications for maternal health

The initial conditions of isolated star formation: IV - C18O observations and modelling of the pre-stellar core L1689B

We present C18O observations of the pre-stellar core L1689B, in the (J=3-2) and (J=2-1) rotational transitions, taken at the James Clerk Maxwell Telescope in Hawaii. We use a lambda-iteration radiative transfer code to model the data. We adopt a similar form of radial density profile to that which we have found in all pre-stellar cores, with a `flat' inner profile, steepening towards the edge, but we make the gradient of the `flat' region a free parameter. We find that the core is close to virial equilibrium, but there is tentative evidence for core contraction. We allow the temperature to vary with a power-law form and find we can consistently fit all of the CO data with an inverse temperature gradient that is warmer at the edge than the centre. However, when we combine the CO data with the previously published millimetre data we fail to find a simultaneous fit to both data-sets without additionally allowing the CO abundance to decrease towards the centre. This effect has been observed qualitatively many times before, as the CO freezes out onto the dust grains at high densities, but we quantify the effect. Hence we show that the combination of mm/submm continuum and spectral line data is a very powerful method of constraining the physical parameters of cores on the verge of forming stars.Comment: 10 pages. Accepted for publication in MNRA

Can self-affirmation exacerbate adverse reactions to stress under certain conditions?

OBJECTIVE: Self-affirmation has repeatedly been shown to reduce adverse psychological and physiological responses to stress. However, it is plausible that self-affirmation could exacerbate negative reactions to stress under certain conditions. The current research explored whether self-affirmation would increase negative psychological responses to a stressor occurring in a central life domain characterised by low levels of control. DESIGN: Female participants (Study 1 N = 132; Study 2 N = 141) completed baseline measures of anxiety and mood. They were then randomly allocated to complete a self-affirmation or control task, before reading a narrative documenting a stressful birth and imagining themselves in the place of the woman giving birth. After completing this task, participants again reported their levels of anxiety and positive mood. MAIN OUTCOME MEASURES: Anxiety and positive mood assessed at follow-up. RESULTS: Study 1 demonstrated that self-affirmed women experienced increased anxiety and less positive mood at follow-up, compared both to baseline and to women in the control condition. Study 2 revealed that the effect of self-affirmation on outcomes was moderated by fear of childbirth. CONCLUSION: These results provide preliminary evidence that self-affirmation may worsen negative responses to stressors under certain conditions and for certain individuals

Artificial water points facilitate the spread of an invasive vertebrate in arid Australia

Summary: The spread of invasive species after their initial introduction is often facilitated by human actions. In some cases, invaders only become established in habitats where dominant native species have been displaced as a result of human actions or where humans inadvertently provide essential resources such as food, water or shelter. We investigated if dams that provide water for livestock have facilitated the cane toad's (Rhinella marina) invasion of a hot semi-arid landscape by providing toads with a resource subsidy and hence refuge from extreme heat and aridity. To determine the relationship between the presence of surface water and habitat occupancy by toads, we surveyed natural and artificial water features for cane toads during the annual dry season. We used radiotracking and acoustic tags to determine whether movement patterns and shelter use of cane toads were focussed around dams. To determine whether dams provide toads with refuge from extreme heat and aridity, we deployed plaster models with internal thermometers to estimate ambient temperatures and toad desiccation rates in shelter sites. To determine whether dams alleviate the stress experienced by toads, we measured plasma corticosterone levels of toads that sheltered in and away from dams. Toads were present in sites with standing water and absent from waterless sites. Most radiotracked toads sheltered within 1 m of water. Toad movements were focussed around water. Toads tracked with passive acoustic telemetry over a 6-month dry season were highly resident at dams. Plaster models placed in toad shelter sites away from the water lost 27% more mass and experienced higher temperatures than models placed near the water's edge. Toads that sheltered in terrestrial shelters exhibited higher plasma corticosterone levels compared to toads that sheltered near dams. Dams provide toads with refuge habitats where they are less at risk from overheating and dehydration. Synthesis and applications. Artificial water points can facilitate biological invasions in arid regions by providing a resource subsidy for water-dependent invasive species. Our study suggests that there is scope to control populations of water-dependent invasive vertebrates in arid regions by restricting their access to artificial water points. © 2014 British Ecological Society