1,141 research outputs found

    The low dimensional dynamical system approach in General Relativity: an example

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    In this paper we explore one of the most important features of the Galerkin method, which is to achieve high accuracy with a relatively modest computational effort, in the dynamics of Robinson-Trautman spacetimes.Comment: 7 pages, 5 figure

    Computing stationary free-surface shapes in microfluidics

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    A finite-element algorithm for computing free-surface flows driven by arbitrary body forces is presented. The algorithm is primarily designed for the microfluidic parameter range where (i) the Reynolds number is small and (ii) force-driven pressure and flow fields compete with the surface tension for the shape of a stationary free surface. The free surface shape is represented by the boundaries of finite elements that move according to the stress applied by the adjacent fluid. Additionally, the surface tends to minimize its free energy and by that adapts its curvature to balance the normal stress at the surface. The numerical approach consists of the iteration of two alternating steps: The solution of a fluidic problem in a prescribed domain with slip boundary conditions at the free surface and a consecutive update of the domain driven by the previously determined pressure and velocity fields. ...Comment: Revised versio

    Furrow application of insecticide as a method of controlling wireworms in potato land

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    Three methods of applying insecticides for the control of the wireworm, <i>Agriotes obscurus</i> L.. were tested using fonofos and terbufos. Most treatments gave significantly more marketable tubers than the control. The furrow treatment gave more consistent results than broadcast or side-dress and, at 1.1 or 2.2 kg a.i/ha, gave control equal to, or better than, the broadcast treatment at 5.6 kg a.i./ha. Analyses by gas chromatography using a flame photometric detector for residues in potatoes grown in treated soil showed residues to be less than 0.02 ppm

    Will the Scottish Cancer Target for the year 2000 be met? The use of cancer registration and death records to predict future cancer incidence and mortality in Scotland.

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    Cancer mortality data reflect disease incidence and the effectiveness of treatment. Incidence data, however, reflect the burden of disease in the population and indicate the need for prevention measures, diagnostic services and cancer treatment facilities. Monitoring of targets mandates that both be considered. The Scottish Cancer Target, established in 1991, proposed that a reduction of 15% in mortality from cancer in the under-65s should be achieved between 1986 and 2000. Each year in Scotland approximately 8300 persons under 65 are diagnosed with cancer and 4500 die from the disease. The most common malignancies, in terms of both incident cases and deaths, in the under-65s, are lung and large bowel cancer in males, and breast, large bowel and lung cancer in females. A decrease of 6% in the number of cancer cases diagnosed in males under 65 is predicted between 1986 and 2000, whereas the number of cases in females in the year 2000 is expected to remain at the 1986 level. In contrast, substantial reductions in mortality are expected for both sexes: 17% and 25% in males and females respectively. Demographic changes will influence the numbers of cancer cases and deaths in the Scottish population in the year 2000. However, long-term trends in the major risk factors, such as smoking, are likely to be the most important determinants of the future cancer burden

    Cigarette Smoking Among Low-Income African Americans: A Serious Public Health Problem

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    Background This study examines the current prevalence of cigarette smoking and the number of cigarettes smoked in a community-based sample of 1021 low-income African-American men and women. Methods Participants were selected using a two-stage, area probability sample design. Data were collected in 2002–2003 in face-to-face interviews and analyzed in 2005. All data and analyses were weighted to account for the complex sampling design. Results Fifty-nine percent of men and 41% of women were current smokers, with younger individuals apparently initiating smoking at an earlier age than older individuals. Conclusions The high prevalence of cigarette use provides further evidence that the excess burden of tobacco-related disease among low-income African-American families may be on the rise. This is of great concern, and if confirmed by further research, indicates an urgent need for preventive intervention

    Dopant-induced crossover from 1D to 3D charge transport in conjugated polymers

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    The interplay between inter- and intra-chain charge transport in bulk polythiophene in the hopping regime has been clarified by studying the conductivity as a function of frequency (up to 3 THz), temperature and doping level. We present a model which quantitatively explains the observed crossover from quasi-one-dimensional transport to three-dimensional hopping conduction with increasing doping level. At high frequencies the conductivity is dominated by charge transport on one-dimensional conducting chains.Comment: 4 pages, 2 figure

    On Rationality

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    Rationality is an enduring topic of interest across the disciplines and has become even more so, given the current crises that are unfolding in our society. The four books reviewed here, which are written by academics working in economics, political science, political theory and philosophy, provide an interdisciplinary engagement with the idea of rationality and the way it has shaped the institutional frameworks and global political economy of our time. Rational choice theory has certainly proved to be a useful analytic tool in certain contexts, and instrumental reason has been a key tenet of human progress in several periods of history, including the industrial revolution and the modernity that emerged in the nineteenth century. Given the complexity of our current challenges, however, is it time to ask whether this paradigm might be better complemented by more holistic and heterodox approaches? Hindmoor A and Taylor TY (2015) Rational Choice (Political Analysis), 2nd edn. London; New York: Palgrave Macmillan. Massumi (2015) The Power at the End of the Economy. Durham: Duke University Press. Brown (2015) Undoing the Demos: Neoliberalism’s Stealth Revolution. New York: Zone Books. Ludovisi SG (ed.) (2015) Critical Theory and the Challenge of Praxis: Beyond Reification. Farnham; Burlington, VT: Ashgate

    Tenfold Magnetoconductance in a Non-Magnetic Metal Film

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    We present magnetoconductance (MC) measurements of homogeneously disordered Be films whose zero field sheet conductance (G) is described by the Efros-Shklovskii hopping law G(T)=(2e2/h)exp(To/T)1/2G(T)=(2e^2/h)\exp{-(T_o/T)^{1/2}}. The low field MC of the films is negative with G decreasing 200% below 1 T. In contrast the MC above 1 T is strongly positive. At 8 T, G increases 1000% in perpendicular field and 500% in parallel field. In the simpler parallel case, we observe {\em field enhanced} variable range hopping characterized by an attenuation of ToT_o via the Zeeman interaction.Comment: 9 pages including 5 figure

    Differential Consumption of Four Aphid Species by Four Lady Beetle Species

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    The acceptability of four different aphid species Macrosiphum albifrons (Essig), Macrosiphum euphorbiae (Thomas), Macrosiphum pseudorosae Patch, and Myzus persicae (Sulzer) (Hemiptera: Aphididae), as prey for four lady beetle species, one native species Coccinella trifasciata L, and three non-native Coccinella septempunctata L, Harmonia axyridis Pallas, Propylea quatuordecimpunctata L (Coleoptera: Coccinellidae) were tested in the laboratory. The relative field abundance of adults of the same lady beetle species on host vegetation, Lupinus polyphyllus Lindley (Fabales: Fabaceae), Solanum tuberosum L (Solanales: Solanaceae), and Rosa multiflora Thunberg (Rosales: Rosaceae), both with and without aphids present was also observed. In the laboratory, H. axyridis generally consumed the most aphids, while P. quatuordecimpunctata consumed the fewest. The exception was P. quatuordecimpunctata, which consumed a greater number of M. albifrons nymphs, and C. trifasciata, which consumed a greater number of M. albifrons nymphs and adults, compared with the other two beetle species. Lady beetles consumed fewer M. albifrons compared with the other three aphid species, likely because of deterrent compounds sequestered by this species from its host plant. In the field, P. quatuordecimpunctata was the most abundant species found on L. polyphyllus and S. tuberosum

    Identification of a gene associated with avian migratory behaviour

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    Bird migration is one of the most spectacular and best-studied phenomena in behavioural biology. Yet, while the patterns of variation in migratory behaviour and its ecological causes have been intensively studied, its genetic, physiological and neurological control remains poorly understood. The lack of knowledge of the molecular basis of migration is currently not only limiting our insight into the proximate control of migration, but also into its evolution. We investigated polymorphisms in the exons of six candidate genes for key behavioural traits potentially linked to migration, which had previously been identified in several bird species, and eight control loci in 14 populations of blackcaps (Sylvia atricapilla), representing the whole range of geographical variation in migration patterns found in this species, with the aim of identifying genes controlling variation in migration. We found a consistent association between a microsatellite polymorphism and migratory behaviour only at one candidate locus: the ADCYAP1 gene. This polymorphism explained about 2.6 per cent of the variation in migratory tendency among populations, and 2.7–3.5% of variation in migratory restlessness among individuals within two independent populations. In all tests, longer alleles were associated with higher migratory activity. The consistency of results among different populations and levels of analysis suggests that ADCYAP1 is one of the genes controlling the expression of migratory behaviour. Moreover, the multiple described functions of the gene product indicate that this gene might act at multiple levels modifying the shift between migratory and non-migratory states
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