Nitrogen Mineralization from Root Residues of Subterranean Clover and Lucerne

To understand why crops grown in the first or second year after lucerne (Medicago sativa L.) yielded less than crops grown after subterranean clover (Trifolium subterraneum L.) despite greater nitrogen (N) fixation by the lucerne, we studied the N mineralization patterns of their root residues in soil incubation assays. Fine roots of both species produced more mineral N than the control soil with no root residues. In contrast, coarse roots mineralized less N than the control soil. These differences in N mineralization were not explained by the physical size and therefore surface area differences between fine and coarse roots. Rather, the differences in N mineralization were explained by differences in the carbon to nitrogen ratio (C:N) of fine and coarse roots. Fine roots of both species had a C:N of about 11, while the C:N of coarse roots ranged from 28 to 37. Empirical evidence suggests that a mineralization / immobilization threshold occurs at a C:N of 20 to 30, and these results are in accordance with this interpretation. However, subterranean clover had mainly fine roots giving a weighted average C:N of 19 for the whole root system, while lucerne had mainly coarse roots giving an average C:N of 26, suggesting that root residues of subterranean clover result in a net mineralization of N while lucerne roots cause a net immobilization of N

Loop corrections to Delta N_eff in large volume models

In large volume models reheating is driven by the decays of the volume modulus to the visible sector, while the decays to its axion partners result in dark radiation. In this article we discuss the impact of loop corrections on the only model-independent visible decay channel: the decay into Higgs pairs via a Giudice-Masiero term. Including such radiative effects leads to a more precise determination of the relative fraction of dark radiation, since by contrast all loop corrections to the volume axion decay mode are Planck suppressed. Assuming an MSSM spectrum and that the Giudice-Masiero coupling is fixed at the string scale by a shift symmetry in the Higgs sector, we arrive at a prediction for the effective number of neutrinos. The result turns out to be too large to be consistent with data, highly disfavouring the minimal model.Comment: 14 pages, 3 figures; v2: Version to appear in JHEP. Expanded introduction to clarify arguments, assumptions and applicability of results; added reference

Selection on non-social traits limits the invasion of social cheats

While the conditions that favour the maintenance of cooperation have been extensively investigated, the significance of non-social selection pressures on social behaviours has received little attention. In the absence of non-social selection pressures, patches of cooperators are vulnerable to invasion by cheats. However, we show both theoretically, and experimentally with the bacterium Pseudomonas fluorescens, that cheats may be unable to invade patches of cooperators under strong non-social selection (both a novel abiotic environment and to a lesser extent, the presence of a virulent parasite). This is because beneficial mutations are most likely to arise in the numerically dominant cooperator population. Given the ubiquity of novel selection pressures on microbes, these results may help to explain why cooperation is the norm in natural populations of microbes

Eliminating latent tuberculosis in low-burden settings: are the principal beneficiaries to be disadvantaged groups or the broader population?

Tuberculosis (TB) remains a leading cause of morbidity and mortality worldwide, and the burdens of this disease continue to track prior disadvantage. In order to galvanise a coordinated global response, WHO has recently launched the End TB Campaign that aims to eliminate TB by 2050. Key to this is the introduction of population screening programmes in low-burden settings to identify and treat people who have latent TB infection (LTBI). The defining features of LTBI are: that it is not an active disease but confers an increased risk of disease; the socially disadvantaged are those most in danger and uncertainty persists as to who will be harmed or benefitted from screening-led prophylactic interventions. Systematic screening programmes that include surveillance, case-finding and treatment of asymptomatic individuals inevitably redistribute the risk of harms and the potential for benefits within a population. The extent to which those targeted within such programmes should be exposed to higher levels of risk in the pursuit of individual or community benefits requires careful consideration prior to implementation. As currently construed, it remains unclear who stands to benefit most from how LTBI screening in high-income countries is being organised, and whose health is being prioritised: members of disadvantaged groups or the broader community. Unless the aims of LTBI screening programmes in these settings are made transparent and their prioritisation ethically justified, there is a significant danger that such a targeted intervention will further disadvantage those who have the least capacity to bear the burdens of TB elimination.NHMRC Centre for Research Excellence in TB Control (CRE 1043225)

Playing for high stakes: Findings from the Irish neighbourhood play research project and their implications for education

The Irish Neighbourhood Play Research Project included almost 1700 families and 240 communities throughout Ireland. The findings hold clear implications for educational policy and practice. Using surveys, interviews and naturalistic observation, data was secured on how children in modern Ireland aged 0 - 15 are playing. An all-island approach was taken incorporating cities, towns and rural areas across a variety of socio-economic groupings. Interesting findings arose from the data relating to generational differences in levels of freedom, play, exercise, engagement with risk, with nature, with scheduled/timetabled extracurricular activities, with homework, with electronics, with creative activities and with traditional play types and games. Differences in play choices and experiences were also evident across socio-economic groupings, community types, gender lines, age ranges and housing types. This paper presents the data and asks what it means within a framework of educational implication. Most importantly: what can education do to redress these implications? Innovations in pedagogy and policy are required to meet the educational challenges implicit within this data. This ground breaking research on the changing face of childhood points clearly to the need for collaborative, co- participative, democratic, empowering and playful pedagogies and educational policies which support them

Spiral Galaxies Rotation Curves with a Logarithmic Corrected Newtonian Gravitational Potential

We analyze the rotation curves of 10 spiral galaxies with a newtonian potential corrected with an extra logarithmic term, using a disc modelization for the spiral galaxies. There is a new constant associated with the extra term in the potential. The rotation curve of the chosen sample of spiral galaxies is well reproduced for a given range of the new constant. It is argued that this correction can have its origin from string configurations. The compatibility of this correction with local physics is discussed.Comment: Latex file, 6 pages, 20 figure

Injury Alcohol-Attributable Fractions: Methodological Issues and Developments

Background: Alcohol-attributable fractions (AAFs) are routinely used to estimate the burden of injury resulting from alcohol. Recent methodological advances allow AAFs to be estimated using national survey data. However, this requires assuming that the drinking patterns are equivalent to those used by epidemiological studies estimating the relative risk of injury. This study explores the implications of this assumption and presents an improved method of estimating injury AAFs. Methods: Diary survey is used to describe individuals’ drinking occasions and estimate AAFs. Statistical methods and numerical integration are used to combine the evidence on the risk of injury when intoxicated with the diary data. Alternative assumptions are chosen to explore the implications of using national survey data. Results:Overall, an estimated 27% of road traffic accident (RTA) and 23% of non-RTA injuries in Britain are attributable to alcohol. AAF estimates for RTAs range from 54% to 2% and for non-RTAs from 36% to 8% in men aged 16-24 and women aged 55-64 respectively. Two potentially more realistic assumptions relating to the use of national survey data resulted in substantially lower AAF estimates for RTAs. Conclusion: Current methods of estimating injury AAFs using national survey data are flawed for some harms, particularly RTAs, where the data is not consistent with the epidemiological literature. Our findings indicate that the burden of injuries from RTAs in England has been previously overestimated. Further research into the prevalence of risky behaviours when intoxicated is required to refine these methods and produce more robust burden of injury estimates

Functional network changes and cognitive control in schizophrenia

Cognitive control is a cognitive and neural mechanism that contributes to managing the complex demands of day-to-day life. Studies have suggested that functional impairments in cognitive control associated brain circuitry contribute to a broad range of higher cognitive deficits in schizophrenia. To examine this issue, we assessed functional connectivity networks in healthy adults and individuals with schizophrenia performing tasks from two distinct cognitive domains that varied in demands for cognitive control, the RiSE episodic memory task and DPX goal maintenance task. We characterized general and cognitive control-specific effects of schizophrenia on functional connectivity within an expanded frontal parietal network (FPN) and quantified network topology properties using graph analysis. Using the network based statistic (NBS), we observed greater network functional connectivity in cognitive control demanding conditions during both tasks in both groups in the FPN, and demonstrated cognitive control FPN specificity against a task independent auditory network. NBS analyses also revealed widespread connectivity deficits in schizophrenia patients across all tasks. Furthermore, quantitative changes in network topology associated with diagnostic status and task demand were observed. The present findings, in an analysis that was limited to correct trials only, ensuring that subjects are on task, provide critical insights into network connections crucial for cognitive control and the manner in which brain networks reorganize to support such control. Impairments in this mechanism are present in schizophrenia and these results highlight how cognitive control deficits contribute to the pathophysiology of this illness