412 research outputs found

    Nucleon structure from mixed action calculations using 2+1 flavors of asqtad sea and domain wall valence fermions

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    We present high statistics results for the structure of the nucleon from a mixed-action calculation using 2+1 flavors of asqtad sea and domain wall valence fermions. We perform extrapolations of our data based on different chiral effective field theory schemes and compare our results with available information from phenomenology. We discuss vector and axial form factors of the nucleon, moments of generalized parton distributions, including moments of forward parton distributions, and implications for the decomposition of the nucleon spin.Comment: 68 pages, 47 figures. Main revision points: improved discussion of chiral fits and systematic uncertainties, several minor refinements. Accepted for publication in Phys.Rev.

    Nucleon Generalized Parton Distributions from Full Lattice QCD

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    We present a comprehensive study of the lowest moments of nucleon generalized parton distributions in N_f=2+1 lattice QCD using domain wall valence quarks and improved staggered sea quarks. Our investigation includes helicity dependent and independent generalized parton distributions for pion masses as low as 350 MeV and volumes as large as (3.5 fm)^3, for a lattice spacing of 0.124 fm. We use perturbative renormalization at one-loop level with an improvement based on the non-perturbative renormalization factor for the axial vector current, and only connected diagrams are included in the isosinglet channel.Comment: 40 pages, 49 figures; Revised chiral extrapolations in sections A-K, main conclusions unchange

    Finite volume corrections to the electromagnetic current of the nucleon

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    We compute corrections to both the isovector anomalous magnetic moment and the isovector electromagnetic current of the nucleon to O(p3)O(p^3) in the framework of covariant two-flavor Baryon Chiral Perturbation Theory. We then apply these corrections to lattice data for the anomalous magnetic moment from the LHPC, RBC & UKQCD and QCDSF collaborations

    Non-tariff and overall protection: evidence across countries and over time

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    This paper analyzes the evolution of the incidence and intensity of non-tariff measures (NTMs). It extends earlier work by measuring protection from NTMs over time from a newly available database and provides evidence on the evolution of NTMs. In particular, building on Kee, Nicita and Olarreaga (2009), this paper estimates the ad valorem equivalents (AVEs) of NTMs for 97 countries at the product level over the period 1997 to 2015. We show that the incidence and the intensity of NTMs were both increasing over this period, with NTMs becoming an even more dominant source of trade protection. We are also able to investigate the evolution of overall protection derived jointly fromtariffs and NTMs. The results show that the overall protection level, for most countries and products, has not decreased despite the fall in tariffs associated with multilateral, regional and bilateral trade agreements in recent decades. We also document an increase in overall trade protection during the recent 2008 financial crisis. Overall, this study sheds light on an under-researched aspect of trade liberalization: the proliferation and increase of NTMs

    YAP1 Recruits c-Abl to Protect Angiomotin-Like 1 from Nedd4-Mediated Degradation

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    Tissue development and organ growth require constant remodeling of cell-cell contacts formed between epithelial cells. The Hippo signaling cascade curtails organ growth by excluding the transcriptional co-activator Yes Associated Protein 1 (YAP1) from the nucleus. Angiomotin family members recruit YAP1 to tight junctions [1], but whether YAP1 plays a specific role outside of the nucleus is currently unknown.The present study demonstrates that the E3 ubiquitin ligase Nedd4.2 targets Angiomotin-like 1 (AMOTL1), a family member that promotes the formation of epithelial tight junctions, for ubiquitin-dependent degradation. Unexpectedly, YAP1 antagonizes the function of Nedd4.2, and protects AMOTL1 against Nedd4.2-mediated degradation. YAP1 recruits c-Abl, a tyrosine kinase that binds and phosphorylates Nedd4.2 on tyrosine residues, thereby modifying its ubiquitin-ligase activity.Our results uncover a novel function for cytoplasmic YAP1. YAP1 recruits c-Abl to protect AMOTL1 against Nedd4.2-mediated degradation. Thus, YAP1, excluded from the nucleus, contributes to the maintenance of tight junctions

    Nucleon axial and pseudoscalar form factors from the covariant Faddeev equation

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    We compute the axial and pseudoscalar form factors of the nucleon in the Dyson-Schwinger approach. To this end, we solve a covariant three-body Faddeev equation for the nucleon wave function and determine the matrix elements of the axialvector and pseudoscalar isotriplet currents. Our only input is a well-established and phenomenologically successful ansatz for the nonperturbative quark-gluon interaction. As a consequence of the axial Ward-Takahashi identity that is respected at the quark level, the Goldberger-Treiman relation is reproduced for all current-quark masses. We discuss the timelike pole structure of the quark-antiquark vertices that enters the nucleon matrix elements and determines the momentum dependence of the form factors. Our result for the axial charge underestimates the experimental value by 20-25% which might be a signal of missing pion-cloud contributions. The axial and pseudoscalar form factors agree with phenomenological and lattice data in the momentum range above Q^2 ~ 1...2 GeV^2.Comment: 17 pages, 7 figures, 1 tabl

    Large UK retailers' initiatives to reduce consumers' emissions: a systematic assessment

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    In the interest of climate change mitigation, policy makers, businesses and non-governmental organisations have devised initiatives designed to reduce in-use emissions whilst, at the same time, the number of energy-consuming products in homes, and household energy consumption, is increasing. Retailers are important because they are at the interface between manufacturers of products and consumers and they supply the vast majority of consumer goods in developed countries like the UK, including energy using products. Large retailers have a consistent history of corporate responsibility reporting and have included plans and actions to influence consumer emissions within them. This paper adapts two frameworks to use them for systematically assessing large retailers’ initiatives aimed at reducing consumers’ carbon emissions. The Framework for Strategic Sustainable Development (FSSD) is adapted and used to analyse the strategic scope and coherence of these initiatives in relation to the businesses’ sustainability strategies. The ISM ‘Individual Social Material’ framework is adapted and used to analyse how consumer behaviour change mechanisms are framed by retailers. These frameworks are used to analyse eighteen initiatives designed to reduce consumer emissions from eight of the largest UK retail businesses, identified from publicly available data. The results of the eighteen initiatives analysed show that the vast majority were not well planned nor were they strategically coherent. Secondly, most of these specific initiatives relied solely on providing information to consumers and thus deployed a rather narrow range of consumer behaviour change mechanisms. The research concludes that leaders of retail businesses and policy makers could use the FSSD to ensure processes, and measurements are comprehensive and integrated, in order to increase the materiality and impact of their initiatives to reduce consumer emissions in use. Furthermore, retailers could benefit from exploring different models of behaviour change from the ISM framework in order to access a wider set of tools for transformative system change
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