2,171 research outputs found

    GridWeaver: A Fully-Automatic System for Microarray Image Analysis Using Fast Fourier Transforms

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    Experiments using microarray technology generate large amounts of image data that are used in the analysis of genetic function. An important stage in the analysis is the determination of relative intensities of spots on the images generated. This paper presents GridWeaver, a program that reads in images from a microarray experiment, automatically locates subgrids and spots in the images, and then determines the spot intensities needed in the analysis of gene function. Automatic gridding is performed by running Fast Fourier Transforms on pixel intensity sums. Tests on several data sets show that the program responds well even on images that have significant noise, both random and systemic

    Riemannian submersions from almost contact metric manifolds

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    In this paper we obtain the structure equation of a contact-complex Riemannian submersion and give some applications of this equation in the study of almost cosymplectic manifolds with Kaehler fibres.Comment: Abh. Math. Semin. Univ. Hamb., to appea

    Swinging Atwood's Machine: Experimental and Theoretical Studies

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    A Swinging Atwood Machine (SAM) is built and some experimental results concerning its dynamic behaviour are presented. Experiments clearly show that pulleys play a role in the motion of the pendulum, since they can rotate and have non-negligible radii and masses. Equations of motion must therefore take into account the inertial momentum of the pulleys, as well as the winding of the rope around them. Their influence is compared to previous studies. A preliminary discussion of the role of dissipation is included. The theoretical behaviour of the system with pulleys is illustrated numerically, and the relevance of different parameters is highlighted. Finally, the integrability of the dynamic system is studied, the main result being that the Machine with pulleys is non-integrable. The status of the results on integrability of the pulley-less Machine is also recalled.Comment: 37 page

    The skype paradox:Homelessness and selective intimacy in the use of communications technology

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    Digital technologies are likely to be appropriated by the homeless just as they are by other segments of society. However, these appropriations will reflect the particularities of their circumstances. What are these appropriations? Are they beneficial or effective? Can Skype, as a case in point, assuage the social disconnection that must be, for many, the experience of being homeless? This paper analyses some evidence about these questions and, in particular, the ways communications media are selected, oriented to and accounted for by the homeless young. Using data from a small corpus of interviews, it examines the specific ways in which choice of communication (face-to-face, social media, or video, etc.), are described by these individuals as elected for tactical and strategic reasons having to do with managing their family relations. These relations are massively important both in terms of how communications media are deployed, and in terms of being one of the sources of the homeless state the young find themselves in. The paper examines some of the methodical ways these issues are articulated and the type of ‘causal facticity’ thereby constituted in interview talk. The paper also remarks on the paradoxical problem that technologies like Skype provide: at once allowing people in the general to communicate but in ways that the homeless young want to resist in the particular. The consequences of this for the shaping of communications technology in the future are remarked upon. © John Benjamins Publishing Company

    Habitable Zones of Host Stars During the Post-MS Phase

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    A star will become brighter and brighter with stellar evolution, and the distance of its habitable zone will become farther and farther. Some planets outside the habitable zone of a host star during the main sequence phase may enter the habitable zone of the host star during other evolutionary phases. A terrestrial planet within the habitable zone of its host star is generally thought to be suited to life existence. Furthermore, a rocky moon around a giant planet may be also suited to life survive, provided that the planet-moon system is within the habitable zone of its host star. Using Eggleton's code and the boundary flux of habitable zone, we calculate the habitable zone of our Solar after the main sequence phase. It is found that Mars' orbit and Jupiter's orbit will enter the habitable zone of Solar during the subgiant branch phase and the red giant branch phase, respectively. And the orbit of Saturn will enter the habitable zone of Solar during the He-burning phase for about 137 million years. Life is unlikely at any time on Saturn, as it is a giant gaseous planet. However, Titan, the rocky moon of Saturn, may be suitable for biological evolution and become another Earth during that time. For low-mass stars, there are similar habitable zones during the He-burning phase as our Solar, because there are similar core masses and luminosities for these stars during that phase.Comment: 6 pages, 7 figures. Accepted by Ap & S

    Religious diversity, empathy, and God images : perspectives from the psychology of religion shaping a study among adolescents in the UK

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    Major religious traditions agree in advocating and promoting love of neighbour as well as love of God. Love of neighbour is reflected in altruistic behaviour and empathy stands as a key motivational factor underpinning altruism. This study employs the empathy scale from the Junior Eysenck Impulsiveness Questionnaire to assess the association between empathy and God images among a sample of 5993 religiously diverse adolescents (13–15 years old) attending state maintained schools in England, Northern Ireland, Scotland, Wales, and London. The key psychological theory being tested by these data concerns the linkage between God images and individual differences in empathy. The data demonstrate that religious identity (e.g. Christian, Muslim) and religious attendance are less important than the God images which young people hold. The image of God as a God of mercy is associated with higher empathy scores, while the image of God as a God of justice is associated with lower empathy scores

    Random Mass Dirac Fermions in Doped Spin-Peierls and Spin-Ladder systems: One-Particle Properties and Boundary Effects

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    Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized by a gap in the spin-excitation spectrum, which can be modeled at low energies by that of Dirac fermions with a mass. In the presence of disorder these systems can still be described by a Dirac fermion model, but with a random mass. Some peculiar properties, like the Dyson singularity in the density of states, are well known and attributed to creation of low-energy states due to the disorder. We take one step further and study single-particle correlations by means of Berezinskii's diagram technique. We find that, at low energy ϵ\epsilon, the single-particle Green function decays in real space like G(x,ϵ)(1/x)3/2G(x,\epsilon) \propto (1/x)^{3/2}. It follows that at these energies the correlations in the disordered system are strong -- even stronger than in the pure system without the gap. Additionally, we study the effects of boundaries on the local density of states. We find that the latter is logarithmically (in the energy) enhanced close to the boundary. This enhancement decays into the bulk as 1/x1/\sqrt{x} and the density of states saturates to its bulk value on the scale Lϵln2(1/ϵ)L_\epsilon \propto \ln^2 (1/\epsilon). This scale is different from the Thouless localization length λϵln(1/ϵ)\lambda_\epsilon\propto\ln (1/\epsilon). We also discuss some implications of these results for the spin systems and their relation to the investigations based on real-space renormalization group approach.Comment: 26 pages, LaTex, 9 PS figures include

    Network development in biological gels: role in lymphatic vessel development

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    In this paper, we present a model that explains the prepatterning of lymphatic vessel morphology in collagen gels. This model is derived using the theory of two phase rubber material due to Flory and coworkers and it consists of two coupled fourth order partial differential equations describing the evolution of the collagen volume fraction, and the evolution of the proton concentration in a collagen implant; as described in experiments of Boardman and Swartz (Circ. Res. 92, 801–808, 2003). Using linear stability analysis, we find that above a critical level of proton concentration, spatial patterns form due to small perturbations in the initially uniform steady state. Using a long wavelength reduction, we can reduce the two coupled partial differential equations to one fourth order equation that is very similar to the Cahn–Hilliard equation; however, it has more complex nonlinearities and degeneracies. We present the results of numerical simulations and discuss the biological implications of our model
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