The overlap operator as a continued fraction

We use a continued fraction expansion of the sign-function in order to obtain a five dimensional formulation of the overlap lattice Dirac operator. Within this formulation the inverse of the overlap operator can be calculated by a single Krylov space method where nested conjugate gradient procedures are avoided. We show that the five dimensional linear system can be made well conditioned using equivalence transformations on the continued fractions. This is of significant importance when dynamical overlap fermions are simulated.Comment: 3 pages, 1 figure, talk presented by U. Wenger at Lattice2001(chiral

An integrated map of structural variation in 2,504 human genomes

Structural variants are implicated in numerous diseases and make up the majority of varying nucleotides among human genomes. Here we describe an integrated set of eight structural variant classes comprising both balanced and unbalanced variants, which we constructed using short-read DNA sequencing data and statistically phased onto haplotype blocks in 26 human populations. Analysing this set, we identify numerous gene-intersecting structural variants exhibiting population stratification and describe naturally occurring homozygous gene knockouts that suggest the dispensability of a variety of human genes. We demonstrate that structural variants are enriched on haplotypes identified by genome-wide association studies and exhibit enrichment for expression quantitative trait loci. Additionally, we uncover appreciable levels of structural variant complexity at different scales, including genic loci subject to clusters of repeated rearrangement and complex structural variants with multiple breakpoints likely to have formed through individual mutational events. Our catalogue will enhance future studies into structural variant demography, functional impact and disease association. © 2015 Macmillan Publishers Limited. All rights reserved

Evaluating summarised radionuclide concentration ratio datasets for wildlife

Concentration ratios (CRwo-media) are used in most radioecological models to predict whole-body radionuclide activity concentrations in wildlife from those in environmental media. This simplistic approach amalgamates the various factors influencing transfer within a single generic value and, as a result, comparisons of model predictions with site-specific measurements can vary by orders of magnitude. To improve model predictions, the development of 'condition-specific' CRwo-media values has been proposed (e.g. for a specific habitat). However, the underlying datasets for most CRwo-media value databases, such as the wildlife transfer database (WTD) developed within the IAEA EMRAS II programme, include summarised data. This presents challenges for the calculation and subsequent statistical evaluation of condition-specific CRwo-media values. A further complication is the common use of arithmetic summary statistics to summarise data in source references, even though CRwo-media values generally tend towards a lognormal distribution and should, therefore, be summarised using geometric statistics. In this paper, we propose a statistically-defensible and robust method for reconstructing underlying datasets to calculate condition-specific CRwo-media values from summarised data and deriving geometric summary statistics. This method is applied to terrestrial datasets from the WTD. Statistically significant differences in sub-category CRwo-media values (e.g. mammals categorised by feeding strategy) were identified, which may justify the use of these CRwomedia values for specific assessment contexts. However, biases and limitations within the underlying datasets of the WTD explain some of these differences. Given the uncertainty in the summarised CRwo-media values, we suggest that the CRwo-media approach to estimating transfer is used with caution above screening-level assessments

The Political Culture of Poaching: A case study from Northern Greece

Poaching has deep social and cultural roots and its meanings are multi-layered. This article explores the meanings attached to the practice of illegal hunting and fishing around Lake Kerkini in northern Greece. Here poaching must be considered in the context of a disordered ecosystem, where the dominance of locally maligned fish and bird species results from economic and environmental policy designed to benefit distant farmers. We conclude that poaching cannot be understood only as an individual action, but as one where collective and personal identities are defended in the face of seemingly irrevocable economic and social decline. The discussion shows that poachers identify different kinds of poaching. Some of the most apparent forms of poaching, done by local inhabitants, may be less damaging than other commercially oriented forms, including by outsiders. Poaching is motivated through a complex mix of factors. Our data lead us to discuss two manifestations of poaching (a) poaching as a form of collective resistance; and (b) poaching as a violation of culturally valued types of human-nature interaction. Some people who admit undertaking what they perceive as least detrimental forms of poaching are antagonistic towards what they construe to be truly harmful forms. Such people appear willing to act and to support actions against types of poaching they agree to be threatening. This is a message with potential importance for environmental management strategy

Organic matter in space: from star dust to the Solar System

Organic compounds of high degree of complexity are now known to be widespread in the Universe, ranging from objects in our Solar System to distant galaxies. Through the techniques of millimeter-wave spectroscopy, over 140 molecules have been identified through their rotational transitions. Space infrared spectroscopy has detected the stretching and bending modes of compounds with aromatic and aliphatic structures. Analyses of samples of meteorites, comets, asteroids, and interplanetary dust also revealed a rich content of organic substances, some of which could be of extra-solar origin. We review the current state of understanding of the origin, evolution, nature, and distribution of organic matter in space. Also discussed are a number of unexplained astronomical phenomena whose origins could be traced to organic carriers. © 2008 Springer Science+Business Media B.V.link_to_subscribed_fulltex