682 research outputs found

    No future in archaeological heritage management?

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    Although the future is mentioned frequently in overarching aims and visions, and it is a major drive in the daily work of archaeological heritage managers and indeed heritage professionals more generally, it remains unclear precisely how an overall commitment to the future can best inform specific heritage practices. It seems that most archaeologists and other heritage professionals cannot easily express how they conceive of the future they work for, and how their work will impact on that future. The future tends to remain implicit in daily practice which operates in a continuing, rolling present. The authors argue that this needs to change because present-day heritage management may be much less beneficial for the future than we commonly expect

    Including nonlocality in exchange-correlation kernel from time-dependent current density functional theory: Application to the stopping power of electron liquids

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    We develop a scheme for building the scalar exchange-correlation (xc) kernel of time-dependent density functional theory (TDDFT) from the tensorial kernel of time-dependent {\em current} density functional theory (TDCDFT) and the Kohn-Sham current density response function. Resorting to the local approximation to the kernel of TDCDFT results in a nonlocal approximation to the kernel of TDDFT, which is free of the contradictions that plague the standard local density approximation (LDA) to TDDFT. As an application of this general scheme, we calculate the dynamical xc contribution to the stopping power of electron liquids for slow ions to find that our results are in considerably better agreement with experiment than those obtained using TDDFT in the conventional LDA.Comment: 6 pages, 3 figures, accepted to Phys. Rev.

    Time-Dependent Density-Functional Theory for the Stopping Power of an Interacting Electron Gas for Slow Ions

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    Based on the time-dependent density-functional theory, we have derived a rigorous formula for the stopping power of an {\it interacting} electron gas for ions in the limit of low projectile velocities. If dynamical correlation between electrons is not taken into account, this formula recovers the corresponding stopping power of {\it noninteracting} electrons in an effective Kohn-Sham potential. The correlation effect, specifically the excitonic one in electron-hole pair excitations, however, is found to considerably enhance the stopping power for intermediately charged ions, bringing our theory into good agreement with experiment.Comment: 4 pages, 1 figure, Accepted to Phys. Rev. B (Rapid Communication

    Learning Rational Functions

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    International audienceRational functions are transformations from words to words that can be defined by string transducers. Rational functions are also captured by deterministic string transducers with lookahead. We show for the first time that the class of rational functions can be learned in the limit with polynomial time and data, when represented by string transducers with lookahead in the diagonal-minimal normal form that we introduce

    Faecal haemoglobin and faecal calprotectin as indicators of bowel disease in patients presenting to primary care with bowel symptoms

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    OBJECTIVE: In primary care, assessing which patients with bowel symptoms harbour significant disease (cancer, higher-risk adenoma or IBD) is difficult. We studied the diagnostic accuracies of faecal haemoglobin (FHb) and faecal calprotectin (FC) in a cohort of symptomatic patients. DESIGN: From October 2013 to March 2014, general practitioners were prompted to request FHb and FC when referring patients with bowel symptoms to secondary care. Faecal samples were analysed for haemoglobin (EIKEN OC-Sensor io) and calprotectin (BÜHLMANN Calprotectin ELISA). Patients triaged to endoscopy were investigated within 6 weeks. All clinicians and endoscopists were blind to the faecal test results. The diagnostic accuracies of FHb and FC for identification of significant bowel disease were assessed. RESULTS: 1043 patients returned samples. FHb was detectable in 57.6% (median 0.4 ”g/g, 95% CI 0.4 to 0.8; range 0–200). FC at 50 ”g/g or above was present in 60.0%. 755 patients (54.6% women, median age 64 years (range 16–90, IQR 52–73)) returned samples and completed colonic investigations. 103 patients had significant bowel disease; the negative predictive values of FHb for colorectal cancer, higher-risk adenoma and IBD were 100%, 97.8% and 98.4%, respectively. Using cut-offs of detectable FHb and/or 200 ”g/g FC detected two further cases of IBD, one higher-risk adenoma and no additional cancers. CONCLUSIONS: In primary care, undetectable FHb is a good ‘rule-out’ test for significant bowel disease and could guide who requires investigation

    Guidelines for the establishment of microbiological criteria for foods

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    O Grupo de Trabalho OcorrĂȘncia MicrobiolĂłgica na Cadeia Alimentar (GTOMCA) do Programa PortFIR considerou de grande importĂąncia o desenvolvimento de um documento que compilasse uma seleção de legislação e de informaçÔes relativas a CritĂ©rios MicrobiolĂłgicos (CM), visando apoiar e facilitar, aos operadores e entidades do setor alimentar, a sua aplicação na validação do processo de produção, na segurança e/ou higiene dos gĂ©neros alimentĂ­cios, na adesĂŁo a boas prĂĄticas de fabrico dos mesmos, e/ou, ainda, na manutenção da sua qualidade durante o seu tempo de vida Ăștil. Deste modo, o GTOMCA desenvolveu o Guia para o estabelecimento de critĂ©rios microbiolĂłgicos em gĂ©neros alimentĂ­cios, que foi publicado em abril de 2017, contemplando a identificação, caraterĂ­sticas e propĂłsito dos CM, os fatores a considerar para a sua definição, nomeadamente: a categoria do alimento, o microrganismo e/ou as suas toxinas, os metabolitos e a virulĂȘncia, os valores limite, o plano de amostragem, o tipo de utilização e consumo assim como o mĂ©todo de anĂĄlise laboratorial, o ponto da cadeia alimentar onde se aplica, as medidas a tomar no caso de resultados nĂŁo satisfatĂłrios e a necessidade de revisĂŁo e atualização dos CM.The Working Group on Microbiological Occurrence on the Food Chain (GTOMCA) of Por tFIR Program considered unanimously, as an important need, the existence of a document with a selection and compilation of existing legislation and information concerning microbiological criteria (CM) as a tool to suppor t and facilitate its application by operators and entities in the food sector to validate the acceptability of the production process or the food safety or hygiene, the obser vance to good manufacturing practices or the maintenance of the food quality during its lifetime. So, GTOMCA developed a Guide for the establishment of microbiological criteria in foodstuf fs, which was published in April 2017, regarding the identification, characteristics and purpose of microbiological criteria, the factors to consider for its definition, identification, characteristics and purpose of CM and, as impor tant factors to consider the food categor y, the micro-organism and its metabolites, toxins and virulence factors, the limit values, the sampling plan, the type of food consumption as well as the analy tical method for testing the food, the point of the food chain where it is applied, the measures to be taken in the event of unsatisfactor y results and the need to review and update of the CM.info:eu-repo/semantics/publishedVersio

    Mycorrhizas and biomass crops: opportunities for future sustainable development

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    Central to soil health and plant productivity in natural ecosystems are in situ soil microbial communities, of which mycorrhizal fungi are an integral component, regulating nutrient transfer between plants and the surrounding soil via extensive mycelial networks. Such networks are supported by plant-derived carbon and are likely to be enhanced under coppiced biomass plantations, a forestry practice that has been highlighted recently as a viable means of providing an alternative source of energy to fossil fuels, with potentially favourable consequences for carbon mitigation. Here, we explore ways in which biomass forestry, in conjunction with mycorrhizal fungi, can offer a more holistic approach to addressing several topical environmental issues, including ‘carbon-neutral’ energy, ecologically sustainable land management and CO2 sequestration

    Contrasting demographic histories revealed in two invasive populations of the dry rot fungus Serpula lacrymans

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    Globalization and international trade have impacted organisms around the world leading to a considerable number of species establishing in new geographic areas. Many organisms have taken advantage of human-made environments, including buildings. One such species is the dry rot fungus Serpula lacrymans, which is the most aggressive wood-decay fungus in indoor environments in temperate regions. Using population genomic analyses of 36 full genome sequenced isolates, we demonstrated that European and Japanese isolates are highly divergent and the populations split 3000–19,000 generations ago, probably predating human influence. Approximately 250 generations ago, the European population went through a tight bottleneck, probably corresponding to the fungus colonization of the built environment in Europe. The demographic history of these populations, probably lead to low adaptive potential. Only two loci under selection were identified using a Fst outlier approach, and selective sweep analyses identified three loci with extended haplotype homozygosity. The selective sweep analyses found signals in genes possibly related to decay of various substrates in Japan and in genes involved DNA replication and protein modification in Europe. Our results suggest that the dry rot fungus independently established in indoor environments in Europe and Japan and that invasive species can potentially establish large populations in new habitats based on a few colonizing individuals

    Can outsiders follow insiders to beat the market? An Event Study on the Stockholm Stock Exchange

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    i Summary Previous studies have indicated that information asymmetries exist on the financial markets. People with access to non-public information could use that information to their advantage when they trade financial instruments. The Swedish Financial Supervisory Authority (FI) is a public authority that works for stability and efficiency on the financial market. In their work for achieving an efficient market is FI trying to minimize the information asymmetries on the market by keeping a record of all trades being done by what the Swedish law classifies as insiders. The record is public information and a way to inform the market about insider transactions, which creates the question: Can the public information on insider trades kept by FI help an investor to make better investments? Yes, it can! In order to examine the question have we performed event studies on different trading strategies that have been based on information from previous studies in the field. The event studies have focused on insider purchases in Small Cap and Mid Cap companies on the Stockholm Stock Exchange during [2007][2008][2009]. We choose to focus on insider purchases because of its higher relevance for other investors than insider sales. Insiders have several reasons to sell shares in their company, for example portfolio diversification and liquidity needs, but they have one main reason to buy shares, to earn money on their investment. We created and tested three different trading strategies based on the insider purchases executed during 2007-2009. The first trading strategy was based on periods of intensive trading, the second strategy was based on large volume transactions and the third strategy was based on short periods of intensive trading where small purchases were excluded. The first two strategies were applied on Small Cap and Mid Cap separately, while the third strategy was applied on the Small Cap only. We have been using a well-established and highly referenced way to perform our event studies. To be able to test the average development statistically have the returns been aggregated through time and through securities. The trading strategies have been tested over 5, 10, 30 and 90 day periods. The results that we have found indicate that outsiders have a possibility to earn abnormal returns in small companies by using the information provided by FI. The strongest positive result that we attained by our tests was an 1.367% cumulative average abnormal return (CAAR) for a 5 day period with the intensive trading strategy on Small Cap companies. It was surprising that all the tests executed showed negative abnormal return over 30 and 90 days, with some of them being negative statistically significant. The results imply that the trading strategies would not be successful for a time-period over 30 and 90 days. The large volume transaction strategy and the third strategy for Small Cap companies did not result in any statistically significant results but showed positive development for 5 day event periods. We conclude through our study that reported insider trading is valuable for outsiders investing in small companies over short time-periods. The results that we found indicate that smaller companies are less efficiently priced than larger companies. i
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