A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars

The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products provide an excellent basis for a comprehensive and sensitive survey of stellar flares - both from targeted active stars and from those observed serendipitously in the half-degree diameter field-of-view of each observation. The 2XMM Catalogue and the associated time-series (`light-curve') data products have been used as the basis for a survey of X-ray flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray light-curves. Where available, we have compared XMM OM UV/optical data with the X-ray light-curves. Our sample contains ~130 flares with well-observed profiles; they originate from ~70 stars. The flares range in duration from ~1e3 to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to ~1e35 erg. Most of the ~30 serendipitously-observed stars have little previously reported information. The hardness-ratio plots clearly illustrate the spectral (and hence inferred temperature) variations characteristic of many flares, and provide an easily accessible overview of the data. We present flare frequency distributions from both target and serendipitous observations. The latter provide an unbiased (with respect to stellar activity) study of flare energetics; in addition, they allow us to predict numbers of stellar flares that may be detected in future X-ray wide-field surveys. The serendipitous sample demonstrates the need for care when calculating flaring rates.Comment: 26 pages, 24 figures. Additional tables and figures available as 4 ancillary files. To be published in Astronomy and Astrophysic

The Latest Himalaya-Climbing Expedition

n/

The challenges of change:Exploring the dynamics of police reform in Scotland

Despite a long tradition of pessimism regarding the scope for meaningful change in police practices, recent structural reforms to police organizations in several European countries suggest that significant change in policing is possible. Drawing on recent research into the establishment and consequences of a national police force in Scotland, this article uses instrumental, cultural and myth perspectives taken from organization theory to examine how change happened and with what effects. It highlights how police reform involves a complex interplay between the strategic aims of government, the cultural norms of police organizations and the importance of alignment with wider views about the nature of the public sector. The article concludes by identifying a set of wider lessons from the experience of organizational change in policing

Immediate reward reinforcement learning for clustering and topology preserving mappings

We extend a reinforcement learning algorithm which has previously been shown to cluster data. Our extension involves creating an underlying latent space with some pre-defined structure which enables us to create a topology preserving mapping. We investigate different forms of the reward function, all of which are created with the intent of merging local and global information, thus avoiding one of the major difficulties with e.g. K-means which is its convergence to local optima depending on the initial values of its parameters. We also show that the method is quite general and can be used with the recently developed method of stochastic weight reinforcement learning [14]

The contribution of community health education to sustainable control of the Neglected Zoonotic Diseases

Effective and sustainable control of the Neglected Zoonoses (NZDs) demands a One Health approach. NZDs largely impact on individuals in low- and middle-income countries, disproportionally affecting resource poor communities with poor access to veterinary and human health services and to clean water and which are intrinsically dependent on animals for their livelihoods. Many NZDs in humans can be treated, but treatment is often complex and expensive. Similarly, while tools for prevention of transmission may exist, they are complex and expensive to adopt at the scale required to be effective. The cost of intervention for NZDs is high when compared to the public health benefits alone, but costs are easily outweighed by full cross sector analysis and when monetary and non-monetary benefits to all stakeholders are considered. Education is a key tool, often overlooked in favor of more complex solutions for the control of NZDs. Successful education programs have been targeted to children of school age for Taenia solium in Kenya, schistosomiasis in Nigeria, and soil transmitted helminths in China. A Snakes and Ladders board game, designed to teach children about schistosomiasis and encourage compliance with mass deworming programs, deployed in Nigerian schools, showed a 67% increase in knowledge of praziquantel and 65% of children who had previously rejected treatment requested the drug at school. For soil transmitted helminths in China, presentation of health information in cartoon format rather than in poster format, showed post-assessment knowledge to be 90% higher. With the rise in affordable smart-phone technology, internet access and airtime in communities in low- and middle- income countries e-education is an increasingly attractive proposition as an intervention tool for the NZDs. The Vicious Worm, a computer based educational health tool that has been designed around the prevention of Taenia Solium has shown remarkable efficacy in affected communities in which it has been deployed with participants applying the principles learned in their communities. This review explores the successes and benefits of education as a control tool for the NZDs

Comparing trends in the Southern Annular Mode and surface westerly jet

We examine trends in the Southern Annular Mode (SAM), and the strength, position and width of the Southern Hemisphere surface westerly wind jet in observations, reanalyses and the Coupled Model Intercomparison Phase 5 (CMIP5) models. First we consider the period over 1951 to 2011, and show that there are differences in the SAM and jet trends between the CMIP5 models, the HadSLP2r gridded sea-level pressure (SLP) dataset, and the Twentieth Century Reanalysis. The relationships between these trends demonstrates that the SAM index cannot be used to directly infer changes in any one kinematic property of the jet. The spatial structure of the observed trends in SLP and zonal winds is shown to be largest, but also most uncertain, in the southeast Pacific. To constrain this uncertainty we include six reanalyses and compare with station based observations of SLP. We find the CMIP5 mean SLP trends generally agree well with the direct observations, despite some climatological biases, while some reanalyses exhibit spuriously large SLP trends. Similarly, over the more reliable satellite era the spatial pattern of CMIP5 SLP trends is in excellent agreement with HadSLP2r, while several reanalyses are not. Then we compare surface winds with a satellite based product, and show that the CMIP5 mean trend is similar to observed in the core region of the westerlies, but that several reanalyses overestimate recent trends. We caution that studies examining the impact of wind changes on the Southern Ocean could be biased by these spuriously large trends in reanalysis products