267 research outputs found

    Beyond "the Relationship between the Individual and Society": broadening and deepening relational thinking in group analysis

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    The question of ‘the relationship between the individual and society’ has troubled group analysis since its inception. This paper offers a reading of Foulkes that highlights the emergent, yet evanescent, psychosocial ontology in his writings, and argues for the development of a truly psychosocial group analysis, which moves beyond the individual/society dualism. It argues for a shift towards a language of relationality, and proposes new theoretical resources for such a move from relational sociology, relational psychoanalysis and the ‘matrixial thinking’ of Bracha Ettinger which would broaden and deepen group analytic understandings of relationality

    On the Progenitors of Core-Collapse Supernovae

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    Theory holds that a star born with an initial mass between about 8 and 140 times the mass of the Sun will end its life through the catastrophic gravitational collapse of its iron core to a neutron star or black hole. This core collapse process is thought to usually be accompanied by the ejection of the star's envelope as a supernova. This established theory is now being tested observationally, with over three dozen core-collapse supernovae having had the properties of their progenitor stars directly measured through the examination of high-resolution images taken prior to the explosion. Here I review what has been learned from these studies and briefly examine the potential impact on stellar evolution theory, the existence of "failed supernovae", and our understanding of the core-collapse explosion mechanism.Comment: 7 Pages, invited review accepted for publication by Astrophysics and Space Science (special HEDLA 2010 issue

    In vitro propagation of Ananas comosus L. Merr. (Morris)

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    Ananas comosus L. Merr. (Morris) commonly known as pineapple, is an economically important fruit in Malaysia. Among the pineapple producers in the world, Malaysia has put massive efforts to fulfill the high domestic and global market demand. Several attempts have been made recently by integrating biotechnology in conventional breeding concerning issues on the shortage production of pineapple fruits. The fruit productivity could be enhanced via a tissue culture system as it might provide the good quality of planting materials in industrial scale throughout the years. Hence, this study was designed to assess the effectiveness of utilizing tissue culture technique to produce sufficient plantlets of pineapple. The procedure involved culturing aseptic axillary buds excised from suckers in treatments with various concentrations of 6-benzylamino purine (BAP) to induce shoot multiplication. The suckers were successfully disinfected by soaking in 100% Clorox for 3 min with 80% survival and free contamination. The best result for this experiment was obtained in MS supplemented with 3.0 mg L-1 BAP, produced the highest no. of shoots per explant with the highest no. of leaves per explant. Besides, it was found that the treatments added with more than 3.0 mg L-1 BAP decreased the number of shoots and leaves per explant. Nevertheless, further advance study especially in quality control should be done to verify the quality of fruits meet the standard for commercialization

    Calculations of binding energies and masses of heavy quarkonia using renormalon cancellation

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    We use various methods of Borel integration to calculate the binding ground energies and masses of b-bbar and t-tbar quarkonia. The methods take into account the leading infrared renormalon structure of the hard+soft part of the binding energies E(s), and of the corresponding quark pole masses m_q, where the contributions of these singularities in M(s) = 2 m_q + E(s) cancel. Beforehand, we carry out the separation of the binding energy into its hard+soft and ultrasoft parts. The resummation formalisms are applied to expansions of m_q and E(s) in terms of quantities which do not involve renormalon ambiguity, such as MSbar quark mass, and alpha_s. The renormalization scales are different in calculations of m_q, E(s) and E(us). The MSbar mass of b quark is extracted, and the binding energies of t-tbar and the peak (resonance) energies for (t+tbar) production are obtained.Comment: 23 pages, 8 double figures, revtex4; the version to appear in Phys.Rev.D; extended discussion between Eqs.(25) and (26); the paragraph between Eqs.(32) and (33) is new and explains the numerical dependence of the residue parameter on the factorization scale; several new references were added; acknowledgments were modified; the numerical results are unchange

    Spiral Multi-component Structure in Pade - Approximant QCD

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    We present a graphical method of analyzing the infra-red fixed point structure of Pade approximant QCD. The analysis shows a spiral multi-component couplant structure as well as an infra-red attractor behavior of PQCD couplant for all flavors 0≀Nf≀160 \le N_{f} \le 16.Comment: 78 pages, 4 tables, 44 graph

    The Life and Death of Barn Beetles: Faunas from Manure and Stored Hay inside Farm Buildings in Northern Iceland

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    This research was funded by the Commonwealth Scholarship Commission and received support from the Research Budget of the Department of Archaeology at the University of Aberdeen. This project was undertaken as part of doctoral studies supervised by Dr Karen Milek, to whom V.F. is especially grateful for her support and advice. Thomas Birch, SigrĂșn Inga GarĂ°arsdĂłttir, and Paul Ledger provided invaluable assistance during fieldwork. V.F. would like to dedicate this paper to Tom and SĂ­a, who met during this fieldwork and are getting married this year. Many people from Fornleifastofnun Íslands – GarĂ°ar GuĂ°mundsson, Ólöf ÞorsteinsdĂłttir, Þóra PĂ©tursdĂłttir, Adolf FriĂ°riksson and Uggi Ævarsson – as well as Unnstein Ingason, ÁgĂșsta Edwald, and Mark Young, helped with fieldwork logistics. Special thanks are due to all the Icelandic farmers and their families who kindly allowed us to collect insects on their farms and provided help when needed: Hermann AĂ°alsteinsson, HermĂ­na FjĂłla IngĂłlfsdĂłttir, GuĂ°mundur SkĂșlason, SigrĂșn Á. FranzdĂłttir, DĂșna MagnĂșsdĂłttir, Sverrir Steinbergsson, Valgeir Þorvaldsson, Reynir Sveinsson, JĂłnas Þór IngĂłlfsson, and Ívar Ólafsson. Eva Panagiotakopulu, Jan Klimaszewski, Ales Smetana, Georges Pelletier, Gabor Pozsgai, and Jenni Stockham helped with some of the beetle identifications. A.J.D. acknowledges the support of National Science Foundation through ARC 1202692. Consultation of the BugsCEP database (Buckland & Buckland, 2006) aided the redaction of this paper. The authors would like to thank David Smith and two anonymous reviewers for insightful comments that helped improve the quality of this paper.Peer reviewedPostprin

    Large-Scale Neighbor-Joining with NINJA

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    Abstract Neighbor-joining is a well-established hierarchical clustering algorithm for inferring phylogenies. It begins with observed distances between pairs of sequences, and clustering order depends on a metric related to those distances. The canonical algorithm requires O(n3) time and O(n2) space for n sequences, which precludes application to very large sequence families, e.g. those containing 100,000 sequences. Datasets of this size are available today, and such phylogenies will play an increasingly important role in comparative genomics studies. Recent algorithmic advances have greatly sped up neighbor-joining for inputs of thousands of sequences, but are limited to fewer than 13,000 sequences on a system with 4GB RAM. In this paper, I describe an algorithm that speeds up neighbor-joining by dramatically reducing the number of distance values that are viewed in each iteration of the clustering procedure, while still computing a correct neighbor-joining tree. This algorithm can scale to inputs larger than 100,000 sequences because of external-memory-efficient data structures. A free implementation may by obtained fro

    The <i>Ectocarpus</i> genome and the independent evolution of multicellularity in brown algae

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    Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related1. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1).We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae, closely related to the kelps (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic2 approaches to explore these and other aspects of brown algal biology further

    Probing eV-scale axions with CAST

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    We have searched for solar axions or other pseudoscalar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup. Whereas we previously have reported results from CAST with evacuated magnet bores (Phase I), setting limits on lower mass axions, here we report results from CAST where the magnet bores were filled with \hefour gas (Phase II) of variable pressure. The introduction of gas generated a refractive photon mass mÎłm_\gamma, thereby achieving the maximum possible conversion rate for those axion masses \ma that match mÎłm_\gamma. With 160 different pressure settings we have scanned \ma up to about 0.4 eV, taking approximately 2 h of data for each setting. From the absence of excess X-rays when the magnet was pointing to the Sun, we set a typical upper limit on the axion-photon coupling of \gag\lesssim 2.17\times 10^{-10} {\rm GeV}^{-1} at 95% CL for \ma \lesssim 0.4 eV, the exact result depending on the pressure setting. The excluded parameter range covers realistic axion models with a Peccei-Quinn scale in the neighborhood of fa∌107f_{\rm a}\sim10^{7} GeV. Currently in the second part of CAST Phase II, we are searching for axions with masses up to about 1.2 eV using \hethree as a buffer gas.Comment: 18 pages, 7 figures. Revised version of the paper after referee's comments. Main changes on the gas sectio
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