230 research outputs found

    Anomalous Chromomagnetic Moments of Quarks and Large Transverse Energy Jets

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    We consider the jet cross sections for gluons coupling to quarks with an anomalous chromomagnetic moment. We then apply this to the deviation and bounds from QCD found in the CDF and D0 Fermilab data, respectively, to find a range of possible values for the anomalous moments. The quadratic and quartic terms in the anomalous moments can fit to the rise of a deviation with transverse energy. Since previous analyses have been done on the top quark total cross section, here we assume the same moment on all quarks except the top and find the range ∣Îșâ€Č∣≡∣Îș/(2mq)∣=1.0±0.3|\kappa'| \equiv |\kappa/(2 m_q)| = 1.0\pm 0.3 TeV−1^{-1} for the CDF data. Assuming the anomalous moment is present only on a charm or bottom quark which is pair produced results in a range ∣Îșb,câ€Č∣=3.5±1.0|\kappa'_{b,c}| = 3.5 \pm 1.0 TeV−1^{-1}. The magnitudes here are compared with anomalous magnetic moments that could account for RbR_b and found to be in the same general range, as well as not inconsistent with LEP and SLD bounds on ΔΓhad\Delta \Gamma_{\text{had}}.Comment: REVTeX, 11 pages, 2 postscript figure

    Bounds on Radii and Magnetic Dipole Moments of Quarks and Leptons from LEP, SLC and HERA

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    Leptons, quarks and gauge bosons are assumed to be pointlike particles in the Standard Model. Stringent bounds on the radii of quarks and leptons and their weak anomalous magnetic moments can be derived from the high-precision measurements at LEP and SLC. We find a model-independent bound of R\lsim 10^{-17}cm for quark and lepton radii. HERA will provide complementary information on the electromagnetic static properties of the quarks and the parameters of the charged quark currents.Comment: 10 pages,latex, 1 ps-figure and style files included as uuencoded compressed file

    Investigating the basis of substrate recognition in the pC221 relaxosome

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    The nicking of the origin of transfer (oriT) is an essential initial step in the conjugative mobilization of plasmid DNA. In the case of staphylococcal plasmid pC221, nicking by the plasmid-specific MobA relaxase is facilitated by the DNA-binding accessory protein MobC; however, the role of MobC in this process is currently unknown. In this study, the site of MobC binding was determined by DNase I footprinting. MobC interacts with oriT DNA at two directly repeated 9 bp sequences, mcb1 and mcb2, upstream of the oriT nic site, and additionally at a third, degenerate repeat within the mobC gene, mcb3. The binding activity of the conserved sequences was confirmed indirectly by competitive electrophoretic mobility shift assays and directly by Surface Plasmon Resonance studies. Mutation at mcb2 abolished detectable nicking activity, suggesting that binding of this site by MobC is a prerequisite for nicking by MobA. Sequential site-directed mutagenesis of each binding site in pC221 has demonstrated that all three are required for mobilization. The MobA relaxase, while unable to bind to oriT DNA alone, was found to associate with a MobC–oriT complex and alter the MobC binding profile in a region between mcb2 and the nic site. Mutagenesis of oriT in this region defines a 7 bp sequence, sra, which was essential for nicking by MobA. Exchange of four divergent bases between the sra of pC221 and the related plasmid pC223 was sufficient to swap their substrate identity in a MobA-specific nicking assay. Based on these observations we propose a model of layered specificity in the assembly of pC221-family relaxosomes, whereby a common MobC:mcb complex presents the oriT substrate, which is then nicked only by the cognate MobA

    Minimum mass of galaxies from BEC or scalar field dark matter

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    Many problems of cold dark matter models such as the cusp problem and the missing satellite problem can be alleviated, if galactic halo dark matter particles are ultra-light scalar particles and in Bose-Einstein condensate (BEC), thanks to a characteristic length scale of the particles. We show that this finite length scale of the dark matter can also explain the recently observed common central mass of the Milky Way satellites (∌107M⊙\sim 10^7 M_\odot) independent of their luminosity, if the mass of the dark matter particle is about 10−22eV10^{-22} eV.Comment: 10 pages, 1 figure, accepted in JCA

    Nurture, nature and some very dubious social skills: An interpretative phenomenological analysis of talent identification practices in elite English youth soccer

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    This paper reports qualitative findings regarding the concepts and practices utilised in talent identification (TI) among professional coaches working in English youth soccer. Using interpretative phenomenological analysis, detailed interviews with seven such coaches are explored, with a view to elucidating the links between understanding, practice, experience and professional context. Findings reveal three superordinate themes, relating to (1) a primarily ‘nurtured’ and trainable understanding of the broad concept of talent itself, (2) an ostensibly contradictory model of semi-static player psychology, and (3) a highly selective mechanism for separating evidence for ‘mental strength’ and ‘social skills’. It is contended that these findings underscore a case for more thorough interrogation of the real worlds inhabited by coaches, such that ideas about ‘good practice’ in TI might be more effectively reconciled with grounded knowledge of the practical everyday necessities of being a coach

    Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometers

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    We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies (\sim11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez & Loeb (2002), whose differential age evolution as a function of cosmic time directly probes H(z). We analyze the 4000 {\AA} break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors. We provide 8 new measurements of H(z) (see Tab. 4), and determine its change in H(z) to a precision of 5-12% mapping homogeneously the redshift range up to z \sim 1.1; for the first time, we place a constraint on H(z) at z \neq 0 with a precision comparable with the one achieved for the Hubble constant (about 5-6% at z \sim 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies. These measurements have been tested to best match a \Lambda CDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z \sim 2.Comment: 34 pages, 15 figures, 6 tables, published in JCAP. It is a companion to Moresco et al. (2012b, http://arxiv.org/abs/1201.6658) and Jimenez et al. (2012, http://arxiv.org/abs/1201.3608). The H(z) data can be downloaded at http://www.physics-astronomy.unibo.it/en/research/areas/astrophysics/cosmology-with-cosmic-chronometer

    Neuroimaging and Responsibility Assessments

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    Could neuroimaging evidence help us to assess the degree of a person’s responsibility for a crime which we know that they committed? This essay defends an affirmative answer to this question. A range of standard objections to this high-tech approach to assessing people’s responsibility is considered and then set aside, but I also bring to light and then reject a novel objection—an objection which is only encountered when functional (rather than structural) neuroimaging is used to assess people’s responsibility

    The participation myth

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    Policy rhetoric around strategies to and the value of increasing participation in the arts has been well documented internationally over more than a decade. But in the UK, which is the focus for this article, targets to increase participation have been consistently missed and there remains a direct correlation between those taking part in cultural activity and their socio-economic status. The starting point for this article is to examine the barriers to increasing participation in the arts and question the way that such policy has been implemented within the English context, which may have relevance for policy making in other countries. What is demonstrated is that policy implementation is influenced by vested interest of those in receipt of funding and that a narrow range of voices, from a powerful cultural elite, are involved in the decision making in the arts. The article makes a case for widening the range of voices heard in decision making in order to support both artistic practice and public engagement

    Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy: the big brother of SN 1998S

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    We present photometric and spectroscopic observations of SN 2013fc, a bright type II supernova (SN) in a circumnuclear star-forming ring in the luminous infrared galaxy ESO 154-G010, observed as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2013fc is both photometrically and spectroscopically similar to the well-studied type IIn SN 1998S and to the bright type II-L SN 1979C. It exhibits an initial linear decline, followed by a short plateau phase and a tail phase with a decline too fast for 56Co decay with full Îł-ray trapping. Initially, the spectrum was blue and featureless. Later on, a strong broad (˜8000 km s-1) H α emission profile became prominent. We apply a STARLIGHT stellar population model fit to the SN location (observed when the SN had faded) to estimate a high extinction of AV = 2.9 ± 0.2 mag and an age of 10_{-2}^{+3} Myr for the underlying cluster. We compare the SN to SNe 1998S and 1979C and discuss its possible progenitor star considering the similarities to these events. With a peak brightness of B = -20.46 ± 0.21 mag, SN 2013fc is 0.9 mag brighter than SN 1998S and of comparable brightness to SN 1979C. We suggest that SN 2013fc was consistent with a massive red supergiant (RSG) progenitor. Recent mass loss probably due to a strong RSG wind created the circumstellar matter illuminated through its interaction with the SN ejecta. We also observe a near-infrared excess, possibly due to newly condensed dust.</p
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