An upper mass limit for the progenitor of the TypeII-P supernova SN1999gi

Masses and progenitor evolutionary states of TypeII supernovae remain almost unconstrained by direct observations. Only one robust observation of a progenitor (SN1987A) and one plausible observation (SN1993J) are available. Neither matched theoretical predictions and in this Letter we report limits on a third progenitor (SN1999gi). The Hubble Space Telescope has imaged the site of the TypeII-P supernova SN1999gi with the WFPC2 in two filters (F606W and F300W) prior to explosion. The distance to the host galaxy (NGC3184) of 7.9Mpc means that the most luminous, massive stars are resolved as single objects in the archive images. The supernova occurred in a resolved, young OB association 2.3kpc from the centre of NGC3184 with an association age of about 4Myrs. Follow-up images of SN1999gi with WFPC2 taken 14 months after discovery determine the precise position of the SN on the pre-explosion frames. An upper limit of the absolute magnitude of the progenitor is estimated (M_v >= -5.1). By comparison with stellar evolutionary tracks this can be interpreted as a stellar mass, and we determine an upper mass limit of 9(+3/-2)M_solar. We discuss the possibility of determining the masses or mass limits for numerous nearby core-collapse supernovae using the HST archive enhanced by our current SNAP programme.Comment: To appear in ApJ Letters, 16 pages, 3 figure

Early Years and Key Stage 1 Mathematics Teaching: Evidence Review

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Probing non-spherical dark halos in the Galactic dwarf galaxies

We construct axisymmetric mass models for dwarf spheroidal (dSph) galaxies in the Milky Way to obtain plausible limits on the non-spherical structure of their dark halos. This is motivated by the fact that the observed luminous parts of the dSphs are actually non-spherical and Cold Dark Matter (CDM) models predict non-spherical virialized dark halos. Our models consider velocity anisotropy of stars $\bar{v^2_R} / \bar{v^2_{\phi}}$, which can vary with the adopted cylindrical coordinates under the assumption $\bar{v^2_z}=\bar{v^2_R}$ for simplicity, and also include an inclination of the system as a fitting parameter to explain the observed line-of-sight velocity dispersion profile. Applying these models to six of the bright dSphs in the Milky Way, we find that the best-fitting cases for most of the dSphs yield oblate and flattened dark halos, irrespective of assumed density profiles in their central parts. We also find that the total mass of the dSphs enclosed within a spheroid with major-axis length of 300 pc varies from $10^6M_{\odot}$ to $10^7M_{\odot}$, contrary to the conclusion from spherical models. This suggests the importance of considering shapes of dark halos in mass models of the dSphs. It is also found that dark halos of the Galactic dSphs may be more flattened than N-body predictions, thereby implying our yet incomplete understanding of baryonic and/or non-baryonic dark matter physics in dwarf galaxy scales.Comment: 13 pages, 9 figures, Accepted for publication in Ap

Comparison of available measurements of the absolute fluorescence yield

The uncertainty in the absolute value of the fluorescence yield is still one of the main contributions to the total error in the reconstruction of the primary energy of ultra-energetic air showers using the fluorescence technique. A significant number of experimental values of the fluorescence yield have been published in the last years, however reported results are given very often in different units (photons/MeV or photons/m) and for different wavelength intervals. In this work we present a comparison of available results normalized to its value in photons/MeV for the 337 nm band at 800 hPa and 293 K. The conversion of photons/m to photons/MeV requires an accurate determination of the energy deposited by the electrons in the field of view of the experimental setup. We have calculated the energy deposition for each experiment by means of a detailed Monte Carlo simulation including when possible the geometrical details of the particular setup. Our predictions on deposited energy, as well as on some geometrical factors, have been compared with those reported by the authors of the corresponding experiments and possible corrections to the fluorescence yields are proposed.Comment: 29 pages, 5 figures Revised version submitted to Astroparticle Physic

Air Fluorescence Relevant for Cosmic-Ray Detection - Summary of the 5th Fluorescence Workshop, El Escorial 2007

High-energy cosmic rays with energies exceeding $10^{17}$ eV are frequently observed by measurements of the fluorescence light induced by air showers. A major contribution to the systematic uncertainties of the absolute energy scale of such experiments is the insufficient knowledge of the fluorescence light yield of electrons in air. The aim of the 5th Fluorescence Workshop was to bring together experimental and theoretical expertise to discuss the latest progress on the investigations of the fluorescence light yield. The results of the workshop will be reviewed as well as the present status of knowledge in this field. Emphasis is given to the fluorescence light yield important for air shower observations and its dependence on atmospheric parameters, like pressure, temperature, and humidity. The effects of the latest results on the light observed from air showers will be discussed.Comment: Nucl. Instr. & Meth. in pres

Evaluation of work-based screening for early signs of alcohol-related liver disease in hazardous and harmful drinkers: the PrevAIL study

Background The direct cost of excessive alcohol consumption to health services is substantial but dwarfed by the cost borne by the workplace as a result of lost productivity. The workplace is also a promising setting for health interventions. The Preventing Alcohol Harm in Liverpool and Knowsley (PrevAIL) project aimed to evaluate a mechanism for detecting the prevalence of alcohol related liver disease using fibrosis biomarkers. Secondary aims were to identify the additive effect of obesity as a risk factor for early liver disease; to assess other impacts of alcohol on work, using a cross-sectional survey. Methods Participants (aged 36-55y) from 13 workplaces participated (March 2011–April 2012). BMI, waist circumference, blood pressure and self-reported alcohol consumption in the previous week was recorded. Those consuming more than the accepted UK threshold (men: >21 units; female: >14 units alcohol) provided a 20 ml venous blood sample for a biomarker test (Southampton Traffic Light Test) and completed an alcohol questionnaire (incorporating the Severity of Alcohol Dependence Questionnaire). Results The screening mechanism enrolled 363 individuals (52 % women), 39 % of whom drank above the threshold and participated in the liver screen (n = 141, complete data = 124 persons). Workplaces with successful participation were those where employers actively promoted, encouraged and facilitated attendance. Biomarkers detected that 30 % had liver disease (25 %, intermediate; 5 % probable). Liver disease was associated with the frequency of visits to the family physician (P = 0.036) and obesity (P = 0.052). Conclusions The workplace is an important setting for addressing alcohol harm, but there are barriers to voluntary screening that need to be addressed. Early detection and support of cases in the community could avert deaths and save health and social costs. Alcohol and obesity should be addressed simultaneously, because of their known multiplicative effect on liver disease risk, and because employers preferred a general health intervention to one that focused solely on alcohol consumption

Health First: An evidence-based alcohol strategy for the UK

Alcohol is taken for granted in the UK today. It is easy to get hold of, increasingly affordable, advertised everywhere and accepted by many as an integral part of daily life. Yet, despite this, the great majority of the population recognise the harm that alcohol causes. They believe that drinking damages health, drives anti social behaviour, harms children and families and creates huge costs for the NHS and the Police. They are right. Every year in the UK, there are thousands of deaths and over a million hospital admissions related to drinking. More than two in five (44%) violent crimes are committed under the influence of alcohol, as are 37% of domesti c violence incidents. One fifth of all violent crime occurs in or near pubs and clubs and 45% of adults avoid town centres at night because of drunken behaviour. The personal, social and economic cost of alcohol has been estimated to be up to £55bn for England and £7.5bn for Scotland. None of this should be taken for granted. The impact of drinking on public health and community safety is so great that radical steps are needed to change our relationship with alcohol. We need to imagine a society where low or no alcohol consumpti on is the norm, drunkenness is socially unacceptable and town centres are safe and welcoming places for everyone to use. Our vision is for a safer, healthier and happier world where the harm caused by alcohol is minimised. This vision is achievable. But only if we tackle the primary drivers of alcohol consumption. The evidence is clear: the most effective way to reduce the harm from alcohol is to reduce the affordability, availability and attractiveness of alcohol products. It is not enough to limit the damage once people are drunk, dependent, ill or dying. We need to intervene earlier in order to reduce consumption across the entire population. The tools are available. The ‘four Ps' of the marketing mix - price, product, promotion and place - are used by alcohol producers and retailers to increase their sales of alcohol. They can also be used by government to reduce alcohol sales, alcohol consumption and alcohol-related harm. Alcohol taxes are an effective public health measure as they raise prices and suppress demand. However, if they do not keep pace with both inflation and incomes, alcohol products will become more affordable over time. This has been the case in the UK. Deep discounting by retailers has also driven down the price of alcohol and encouraged heavy drinkers to maintain dangerous levels of consumption. These problems need to be tackled by a combinati on of more effective fiscal policy and controls on pricing and discounting. Alcohol products are an extraordinary anomaly. Unlike most food products, they are both remarkably harmful and excepti onally lightly regulated. As with other toxic products, the product label ought to communicate the content of the product and the risks of its consumpti on. Regulation should drive out products that appeal to young people while also incentivising the development and sale of lower strength products. The pervasive marketing of alcohol products in the UK is indefensible. Current restrictions are woefully inadequate: children and young people are regularly exposed to alcohol adverti sing in both old and new media. Only a complete ban on all alcohol advertising and sponsorship will make a lasting diff erence. Licensing practice in the UK is out of date. The focus on pubs and bars has allowed shops and supermarkets to become the dominant players in alcohol sales. Consequently, alcohol is now more available than it has ever been. This has driven pre-loading: getting drunk on cheap, shop-bought alcohol before heading out to late-opening night life. Licensing must focus on public health and seek to control the overall availability of alcohol as well as the effects of drunkenness. Beyond these populati on-level approaches, many more targeted measures are needed to reduce alcohol-related harm. Early interventi on by health and social care professionals is an important and underexploited opportunity to prevent problems developing. Stronger drink driving measures are also required. All these measures are needed. Together, they provide a template for an integrated and comprehensive strategy to tackle the harm from alcohol in the UK.Additional co-authors: Gerry McElwee, Dr Kieran Moriarty CBE, Dr Robin Purshouse, Dr Peter Rice, Alison Rogers, George Roycroft , Chit Selvarajah, Don Shenker, Eric Appleby, Dr Nick Sheron, and Colin Shevill

Fluorescence spectroscopy and multi-way techniques. PARAFAC

PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy. © 2013 The Royal Society of Chemistry