Capture and evolution of dust in planetary mean-motion resonances: A fast, semi-analytic method for generating resonantly trapped disc images

Dust grains migrating under Poynting-Robertson drag may be trapped in mean-motion resonances with planets. Such resonantly trapped grains are observed in the solar system. In extrasolar systems, the exozodiacal light produced by dust grains is expected to be a major obstacle to future missions attempting to directly image terrestrial planets. The patterns made by resonantly trapped dust, however, can be used to infer the presence of planets, and the properties of those planets, if the capture and evolution of the grains can be modelled. This has been done with N-body methods, but such methods are computationally expensive, limiting their usefulness when considering large, slowly evolving grains, and for extrasolar systems with unknown planets and parent bodies, where the possible parameter space for investigation is large. In this work, we present a semi-analytic method for calculating the capture and evolution of dust grains in resonance, which can be orders of magnitude faster than N-body methods. We calibrate the model against N-body simulations, finding excellent agreement for Earth to Neptune mass planets, for a variety of grain sizes, initial eccentricities, and initial semimajor axes. We then apply the model to observations of dust resonantly trapped by the Earth. We find that resonantly trapped, asteroidally produced grains naturally produce the ‘trailing blob’ structure in the zodiacal cloud, while to match the intensity of the blob, most of the cloud must be composed of cometary grains, which owing to their high eccentricity are not captured, but produce a smooth disk.We thank James Harrod for assistance in setting up the project, Grant Kennedy for useful discussions, and the anonymous referee for useful suggestions. AS and MW are supported by the European Union through ERC grant number 279973. AJM acknowledges support from Spanish grant AYA 2010/20630, grant number KAW 2012.0150 from the Knut and Alice Wallenberg foundation, and the Swedish Research Council (grant 2011-3991).This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stv04

Systematic review and meta-analysis of the association between childhood overweight and obesity and primary school diet and physical activity policies.

Open Access ArticleObesity is a major public health concern and there are increasing calls for policy intervention. As obesity and the related health conditions develop during childhood, schools are being seen as important locations for obesity prevention, including multifaceted interventions incorporating policy elements. The objective of this systematic review was to evaluate the effects of policies related to diet and physical activity in schools, either alone, or as part of an intervention programme on the weight status of children aged 4 to 11 years. A comprehensive and systematic search of medical, education, exercise science, and social science databases identified 21 studies which met the inclusion criteria. There were no date, location or language restrictions. The identified studies evaluated a range of either, or both, diet and physical activity related policies, or intervention programmes including such policies, using a variety of observational and experimental designs. The policies were clustered into those which sought to affect diet, those which sought to affect physical activity and those which sought to affect both diet and physical activity to undertake random effects meta-analysis. Within the diet cluster, studies of the United States of America National School Lunch and School Breakfast Programs were analysed separately; however there was significant heterogeneity in the pooled results. The pooled effects of the physical activity, and other diet related policies on BMI-SDS were non-significant. The multifaceted interventions tended to include policy elements related to both diet and physical activity (combined cluster), and although these interventions were too varied to pool their results, significant reductions in weight-related outcomes were demonstrated. The evidence from this review suggests that, when implemented alone, school diet and physical activity related policies appear insufficient to prevent or treat overweight or obesity in children, however, they do appear to have an effect when developed and implemented as part of a more extensive intervention programme. Additional evidence is required before recommendations regarding the focus of policies can be made and therefore, increased effort should be made to evaluate the effect of policies and policy containing intervention programmes upon weight status.Medical Research Council (MRC)National Institute for Health Research (NIHR

Air Stable Indium-Gallium-Zinc-Oxide Diodes with a 6.4 GHz Extrinsic Cutoff Frequency Fabricated Using Adhesion Lithography

High speed rectifiers that can be fabricated at low cost whilst still maintaining a high performance are of interest for wireless communication applications. In this letter amorphous indium gallium zinc oxide (a-IGZO) has been used with adhesion lithography (a technique to create asymmetric planar electrodes separated by a nanogap) to fabricate high performance Schottky diode rectifiers. The diode area and junction capacitance can be significantly reduced using this technique, improving device cut-off frequencies. Devices of different widths have been fabricated showing rectification ratios between 103-104. Capacitances measured for devices of various sizes were all on the order of 0.1 pF. By applying ac signals to the diode and measuring the output voltage across a load resistor a cut-off frequency was found. a IGZO diodes with an extrinsic cut-off frequency of 6.4 GHz at a 15 dBM input power have been realized. The devices also show good air stability with little change in current-voltage characteristics after 12 months

Debris Disks: Probing Planet Formation

Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size) typically form in protoplanetary disks. Gas is now seen long into the debris disk phase. Some of this is secondary implying planetesimals have a Solar System comet-like composition, but some systems may retain primordial gas. Ongoing planet formation processes are invoked for some debris disks, such as the continued growth of dwarf planets in an unstirred disk, or the growth of terrestrial planets through giant impacts. Planets imprint structure on debris disks in many ways; images of gaps, clumps, warps, eccentricities and other disk asymmetries, are readily explained by planets at >>5au. Hot dust in the region planets are commonly found (<5au) is seen for a growing number of stars. This dust usually originates in an outer belt (e.g., from exocomets), although an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018

What is the evidence base for integrating health and environmental approaches in the school context to nurture healthier and more environmentally aware young people? A systematic scoping review of global evidence

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordThis scoping review collates empirical and grey literature that examines how schools are acting to nurture healthier and more environmentally aware young people through integrated approaches. Over the last twenty years, integration has been increasing within school contexts. Approaches include teaching and learning, physical environmental adaptations, developing ecologically focused policy, and reorienting wider school culture. We noted a developing discourse around what constitutes evidence in this emerging interdisciplinary field. Developing a better understanding of integrated approaches, and an evidence base of what works and how, could inform interdisciplinary collaboration and enable a clearer message to be communicated to stakeholders about how the school context can nurture healthier and more environmentally aware young people.University of Exete

Emergence of homeostatic epithelial packing and stress dissipation through divisions oriented along the long cell axis.

Cell division plays an important role in animal tissue morphogenesis, which depends, critically, on the orientation of divisions. In isolated adherent cells, the orientation of mitotic spindles is sensitive to interphase cell shape and the direction of extrinsic mechanical forces. In epithelia, the relative importance of these two factors is challenging to assess. To do this, we used suspended monolayers devoid of ECM, where divisions become oriented following a stretch, allowing the regulation and function of epithelial division orientation in stress relaxation to be characterized. Using this system, we found that divisions align better with the long, interphase cell axis than with the monolayer stress axis. Nevertheless, because the application of stretch induces a global realignment of interphase long axes along the direction of extension, this is sufficient to bias the orientation of divisions in the direction of stretch. Each division redistributes the mother cell mass along the axis of division. Thus, the global bias in division orientation enables cells to act collectively to redistribute mass along the axis of stretch, helping to return the monolayer to its resting state. Further, this behavior could be quantitatively reproduced using a model designed to assess the impact of autonomous changes in mitotic cell mechanics within a stretched monolayer. In summary, the propensity of cells to divide along their long axis preserves epithelial homeostasis by facilitating both stress relaxation and isotropic growth without the need for cells to read or transduce mechanical signals.We thank D. Farquharson and S. Townsend at the University College London workshop and Joel Jennings and Richard Adams for help with model development. B.B. and J.B. thank Cancer Research UK, the Biotechnology and Biological Sciences Research Council (BBSRC) (Grant BB/K009001), the French Institut National du Cancer, and Matthieu Piel for support. T.P.J.W. and A.D. were supported by the Engineering and Physical Sciences Research Council. A.R.H. was supported by the BBSRC (Grant BB/K013521 to G.C. and A.K.), and M.L. was supported by the Agency for Science Technology and Research (Singapore) and the Wellcome Trust.This is the accepted manuscript of a paper published in the Proceedings of the National Academy of Sciences (Wyatt et al., PNAS 2015, 112, 18, 5726-5731, doi:10.1073/pnas.1420585112). The final version is available at http://dx.doi.org/10.1073/pnas.142058511

James Hutton’s geological tours of Scotland : romanticism, literary strategies, and the scientific quest

This article explores a somewhat neglected part of the story of the emergence of geology as a science and discourse in the late eighteenth century – James Hutton’s posthumously published accounts of the geological tours of Scotland that he undertook in the years 1785 to 1788 in search of empirical evidence in support of his theory of the Earth and that he intended to include in the projected third volume of his Theory of the Earth of 1795. The article brings some of the assumptions and techniques of literary criticism to bear on Hutton’s scientific travel writing in order to open up new connections between geology, Romantic aesthetics and eighteenth-century travel writing about Scotland. Close analysis of Hutton’s accounts of his field trips to Glen Tilt, Galloway and Arran, supplemented by later accounts of the discoveries at Jedburgh and Siccar Point, reveals the interplay between desire, travel and the scientific quest and foregrounds the textual strategies that Hutton uses to persuade his readers that they share in the experience of geological discovery and interpretation as ‘virtual witnesses’. As well as allowing us to revisit the interrelation between scientific theory and discovery, this article concludes that Hutton was a much better writer than he has been given credit for and suggests that if these geological tours had been published in 1795 they would have made it impossible for critics to dismiss him as an armchair geologist

Cluster randomized trial of an active, multifaceted information dissemination intervention based on The WHO Reproductive health library to change obstetric practices: methods and design issues [ISRCTN14055385]

BACKGROUND: Effective strategies for implementing best practices in low and middle income countries are needed. RHL is an annually updated electronic publication containing Cochrane systematic reviews, commentaries and practical recommendations on how to implement evidence-based practices. We are conducting a trial to evaluate the improvement in obstetric practices using an active dissemination strategy to promote uptake of recommendations in The WHO Reproductive Health Library (RHL). METHODS: A cluster randomized trial to improve obstetric practices in 40 hospitals in Mexico and Thailand is conducted. The trial uses a stratified random allocation based on country, size and type of hospitals. The core intervention consists of three interactive workshops delivered over a period of six months. The main outcome measures are changes in clinical practices that are recommended in RHL measured approximately a year after the first workshop. RESULTS: The design and implementation of a complex intervention using a cluster randomized trial design are presented. CONCLUSION: Designing the intervention, choosing outcome variables and implementing the protocol in two diverse settings has been a time-consuming and challenging process. We hope that sharing this experience will help others planning similar projects and improve our ability to implement change

Circumstellar discs: What will be next?

This prospective chapter gives our view on the evolution of the study of circumstellar discs within the next 20 years from both observational and theoretical sides. We first present the expected improvements in our knowledge of protoplanetary discs as for their masses, sizes, chemistry, the presence of planets as well as the evolutionary processes shaping these discs. We then explore the older debris disc stage and explain what will be learnt concerning their birth, the intrinsic links between these discs and planets, the hot dust and the gas detected around main sequence stars as well as discs around white dwarfs.Comment: invited review; comments welcome (32 pages

(Working title) Are We Meeting Oral Health Needs of Care Home Populations?

Aim: To evaluate care home (N) staff knowledge of oral care in comparison to NHS Quality Improvement Scotland (NHS QIS) guidelines. To identify barriers to delivering oral care and determine if Oral Health Educator (OHE) training had an effect upon staff knowledge of oral care delivery. Setting: The study was undertaken within Greater Glasgow, 2005 to 2007. Subjects and Methods: From 33 care homes (N), 28 participated in data gathering comprising 109 staff. A ‘knowledge check-list’ based upon daily oral care protocol from NHS QIS Best Practice Statement (BPS) served as template for knowledge assessment. An OHE undertook small group discussions related to the BPS in a sub-group of original participants and a second round of data collected. Results: The majority of staff (n=86, 79%) agreed that residents required assistance with oral care and placed oral care (n=85, 78%) as a moderate to high priority. Only 57% of managers and 49% of nurses had received training in oral care. Most staff (79% of managers, 85% of nurses) were unaware of the NHS QIS BPS. Deficiencies in knowledge of key areas within the BPS were identified. Between pre- and post-OHE training, significant differences were identified in prioritisation of oral care (p =0.009), perceived competence (p =0.005) and confidence giving advice (p =0.004). Following OHE intervention, knowledge of BPS protocol increased by 45%. Conclusion: Knowledge of oral care provision by carers for home residents requires substantial improvement. An OHE training programme structured around the NHS QIS BPS demonstrated a measurable increase in levels of staff knowledge of oral care