7,331 research outputs found

    Magnetic variability in the young solar analog KIC 10644253: Observations from the Kepler satellite and the HERMES spectrograph

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    The continuous photometric observations collected by the Kepler satellite over 4 years provide a whelm of data with an unequalled quantity and quality for the study of stellar evolution of more than 200000 stars. Moreover, the length of the dataset provide a unique source of information to detect magnetic activity and associated temporal variability in the acoustic oscillations. In this regards, the Kepler mission was awaited with great expectation. The search for the signature of magnetic activity variability in solar-like pulsations still remained unfruitful more than 2 years after the end of the nominal mission. Here, however, we report the discovery of temporal variability in the low-degree acoustic frequencies of the young (1 Gyr-old) solar analog KIC 10644253 with a modulation of about 1.5 years with significant temporal variations along the duration of the Kepler observations. The variations are in agreement with the derived photometric activity. The frequency shifts extracted for KIC 10644253 are shown to result from the same physical mechanisms involved in the inner sub-surface layers as in the Sun. In parallel, a detailed spectroscopic analysis of KIC 10644253 is performed based on complementary ground-based, high-resolution observations collected by the HERMES instrument mounted on the MERCATOR telescope. Its lithium abundance and chromospheric activity S-index confirm that KIC 10644253 is a young and more active star than the Sun.Comment: Accepted for publication in A&A, 12 pages, 8 figure

    Quantum Pair Creation of Soliton Domain Walls

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    A large body of experimental evidence suggests that the decay of the false vacuum, accompanied by quantum pair creation of soliton domain walls, can occur in a variety of condensed matter systems. Examples include nucleation of charge soliton pairs in density waves [eg. J. H. Miller, Jr. et al., Phys. Rev. Lett. 84, 1555 (2000)] and flux soliton pairs in long Josephon junctions. Recently, Dias and Lemos [J. Math. Phys. 42, 3292 (2001)] have argued that the mass mm of the soliton should be interpreted as a line density and a surface density, respectively, for (2+1)-D and (3+1)-D systems in the expression for the pair production rate. As the transverse dimensions are increased and the total mass (energy) becomes large, thermal activation becomes suppressed, so quantum processes can dominate even at relatively high temperatures. This paper will discuss both experimental evidence and theoretical arguments for the existence of high-temperature collective quantum phenomena

    Determination of the Axial-Vector Weak Coupling Constant with Ultracold Neutrons

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    A precise measurement of the neutron decay ÎČ\beta-asymmetry A0A_0 has been carried out using polarized ultracold neutrons (UCN) from the pulsed spallation UCN source at the Los Alamos Neutron Science Center (LANSCE). Combining data obtained in 2008 and 2009, we report A0=−0.11966±0.00089−0.00140+0.00123A_0 = -0.11966 \pm 0.00089_{-0.00140}^{+0.00123}, from which we determine the ratio of the axial-vector to vector weak coupling of the nucleon gA/gV=−1.27590−0.00445+0.00409g_A/g_V = -1.27590_{-0.00445}^{+0.00409}.Comment: 5 pages, 2 figure

    Complex regional pain syndrome 1 – the Swiss cohort study

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    BACKGROUND: Little is known about the course of Complex Regional Pain Syndrome 1 and potential factors influencing the course of this disorder over time. The goal of this study is a) to set up a database with patients suffering from suspected CRPS 1 in an initial stadium, b) to perform investigations on epidemiology, diagnosis, prognosis, and socioeconomics within the database and c) to develop a prognostic risk assessment tool for patients with CRPS 1 taking into account symptomatology and specific therapies. METHODS/DESIGN: Prospective cohort study. Patients suffering from a painful swelling of the hand or foot which appeared within 8 weeks after a trauma or a surgery and which cannot be explained by conditions that would otherwise account for the degree of pain and dysfunction will be included. In accordance with the recommendations of International Classification of Functioning, Disability and Health (ICF model), standardised and validated questionnaires will be used. Patients will be monitored over a period of 2 years at 6 scheduled visits (0 and 6 weeks, 3, 6, 12, and 24 months). Each visit involves a physical examination, registration of therapeutic interventions, and completion of the various study questionnaires. Outcomes involve changes in health status, quality of life and costs/utility. DISCUSSION: This paper describes the rationale and design of patients with CRPS 1. Ideally, potential risk factors may be identified at an early stage in order to initiate an early and adequate treatment in patients with increased risk for delayed recovery

    Seesaw Neutrino Signals at the Large Hadron Collider

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    We discuss the scenario with gauge singlet fermions (right-handed neutrinos) accessible at the energy of the Large Hadron Collider. The singlet fermions generate tiny neutrino masses via the seesaw mechanism and also have sizable couplings to the standard-model particles. We demonstrate that these two facts, which are naively not satisfied simultaneously, are reconciled in the five-dimensional framework in various fashions, which make the seesaw mechanism observable. The collider signal of tri-lepton final states with transverse missing energy is investigated for two explicit examples of the observable seesaw, taking account of three types of neutrino mass spectrum and the constraint from lepton flavor violation. We find by showing the significance of signal discovery that the collider experiment has a potential to find signals of extra dimensions and the origin of small neutrino masses.Comment: 27 pages, 4 figure

    Rare Z-decay into light CP-odd Higgs bosons: a comparative study in different new physics models

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    Various new physics models predict a light CP-odd Higgs boson (labeled as aa) and open up new decay modes for Z-boson, such as Z→fˉfaZ \to \bar{f} f a, Z→aÎłZ\to a\gamma and Z→aaaZ\to aaa, which could be explored at the GigaZ option of the ILC. In this work we investigate these rare decays in several new physics models, namely the type-II two Higgs doublet model (type-II 2HDM), the lepton-specific two Higgs doublet model (L2HDM), the nearly minimal supersymetric standard model (nMSSM) and the next-to-minimal supersymmetric standard model (NMSSM). We find that in the parameter space allowed by current experiments, the branching ratios can reach 10−410^{-4} for Z→fˉfaZ \to \bar{f} f a (f=b,τf=b,\tau), 10−910^{-9} for Z→aÎłZ\to a\gamma and 10−310^{-3} for Z→aaaZ\to aaa, which implies that the decays Z→fˉfaZ \to \bar{f} f a and Z→aaaZ \to a a a may be accessible at the GigaZ option. Moreover, since different models predict different patterns of the branching ratios, the measurement of these rare decays at the GigaZ may be utilized to distinguish the models.Comment: Version in JHEP (discussions added, errors corrected

    Directed -in vitro- evolution of Precambrian and extant Rubiscos

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    Rubisco is an ancient, catalytically conserved yet slow enzyme, which plays a central role in the biosphere’s carbon cycle. The design of Rubiscos to increase agricultural productivity has hitherto relied on the use of in vivo selection systems, precluding the exploration of biochemical traits that are not wired to cell survival. We present a directed -in vitro- evolution platform that extracts the enzyme from its biological context to provide a new avenue for Rubisco engineering. Precambrian and extant form II Rubiscos were subjected to an ensemble of directed evolution strategies aimed at improving thermostability. The most recent ancestor of proteobacteria -dating back 2.4 billion years- was uniquely tolerant to mutagenic loading. Adaptive evolution, focused evolution and genetic drift revealed a panel of thermostable mutants, some deviating from the characteristic trade-offs in CO2-fixing speed and specificity. Our findings provide a novel approach for identifying Rubisco variants with improved catalytic evolution potential.This work was supported by the REPSOL Research contracts Rubolution (RC020401120018), Rubolution 2.0 (RC 020401140042), the CSIC project PIE-201780E043 and the Australian Research Council grant CE140100015

    The Rewiring of Ubiquitination Targets in a Pathogenic Yeast Promotes Metabolic Flexibility, Host Colonization and Virulence

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    Funding: This work was funded by the European Research Council [http://erc.europa.eu/], AJPB (STRIFE Advanced Grant; C-2009-AdG-249793). The work was also supported by: the Wellcome Trust [www.wellcome.ac.uk], AJPB (080088, 097377); the UK Biotechnology and Biological Research Council [www.bbsrc.ac.uk], AJPB (BB/F00513X/1, BB/K017365/1); the CNPq-Brazil [http://cnpq.br], GMA (Science without Borders fellowship 202976/2014-9); and the National Centre for the Replacement, Refinement and Reduction of Animals in Research [www.nc3rs.org.uk], DMM (NC/K000306/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Acknowledgments We thank Dr. Elizabeth Johnson (Mycology Reference Laboratory, Bristol) for providing strains, and the Aberdeen Proteomics facility for the biotyping of S. cerevisiae clinical isolates, and to Euroscarf for providing S. cerevisiae strains and plasmids. We are grateful to our Microscopy Facility in the Institute of Medical Sciences for their expert help with the electron microscopy, and to our friends in the Aberdeen Fungal Group for insightful discussions.Peer reviewedPublisher PD

    Determination of diquat by flow injection-chemiluminescence

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    A simple, economic, sensitive and rapid method for the determination of the pesticide diquat was described. This new method was based on the coupling of flow injection analysis methodology and direct chemiluminescent detection; to the authors' knowledge, this approach had not been used up to now with this pesticide. It was based on its oxidation with ferricyanide in alkaline medium; significant improvements in the analytical signal were achieved by using high temperatures and quinine as sensitiser. Its high throughput (144 h(-1)), together with its low limit of detection (2 ng mL(-1)), achieved without need of preconcentration steps, permitted the reliable quantification of diquat over the linear range of (0.01-0.6) mu g mL(-1) in samples from different origins (river, tap, mineral and ground waters), even in the presence of a 40-fold concentration of paraquat, a pesticide commonly present in the commercial formulations of diquat.LĂłpez-Paz, JL.; CatalĂĄ-Icardo, M.; AntĂłn Garrido, B. (2009). Determination of diquat by flow injection-chemiluminescence. Analytical and Bioanalytical Chemistry. 394(4):1073-1079. doi:10.1007/s00216-009-2609-zS107310793944Hayes WJ Jr, Laws ER Jr (1991) Handbook of pesticide toxicology, Academic Press, San DiegoUS Environmental Protection Agency. http://www.epa.gov/06WDW/contaminants/dw_contamfs/diquat.html (accessed in August 2008)Horwitz W (2000) Official methods of analysis of AOAC International 17th edition. AOAC International, Gaithersburg, MD, USAHara S, Sasaki N, Takase D, Shiotsuka S, Ogata K, Futagami K, Tamura K (2007) Anal Sci 23(5):523–531Rial Otero R, Cancho Grande B, PĂ©rez Lamela C, Simal Gandara J, Aria Estevez M (2006) J Chromatogr Sci 44(9):539–542Aramendia MA, Borau V, Lafont F, Marinas JM, Moreno JM, Porras JM, Urbano FJ (2006) Food Chem 97(1):181–188Nuñez O, Moyano E, Galceran MT (2004) Anal Chim Acta 525(2):183–190Martinez Vidal JL, Belmonte Vega A, Sanchez Lopez FJ, Garrido Frenich AJ (2004) Chromatogr A 1050(2):179–184Lee XP, Kumazawa T, Fujishiro M, Hasegawa C, Arinobu T, Seno H, Sato K (2004) J Mass Spectrom 39(10):1147–1152De Almeida RM, Yonamine M (2007) J Chromatogr B 853(1–2):260–264De Souza D, Machado SAS (2006) Electroanalysis 18(9):862–872De Souza D, Da Silva MRC, Machado SAS (2006) Electroanalysis 18(23):2305–2313PicĂł Y, Rodriguez R, Manes J (2003) Trends Anal Chem 22(3):133–151Ishiwata T (2004) Bunseki Kagaku 53(8):863–864Carneiro MC, Puignou L, GalcerĂĄn MT (2000) Anal Chim Acta 408:263Luque M, Rios A, Valcarcel M (1998) Analyst 123(11):2383–2387Perez Ruiz T, MartĂ­nez Lozano C, Tomas V (1991) Int J Environ Anal Chem 44(4):243–252Perez Ruiz T, MartĂ­nez Lozano C, Tomas V (1991) Anal Chim Acta 244(1):99–104Townshend A (1990) Analyst 115:495–500LĂłpez Paz JL, CatalĂĄ Icardo M (2008) Anal Chim Acta 625:173–179PawlicovĂĄ Z, Sahuquillo I, CatalĂĄ Icardo M, GarcĂ­a Mateo JV, MartĂ­nez Calatayud J (2006) Anal Sci 22:29–34Albert GarcĂ­a JR, CatalĂĄ Icardo M, MartĂ­nez Calatayud J (2006) Talanta 69:608–614Tomlin CDS (1997) The pesticide manual, 11th edn.The British Crop Protection CouncilUKCatalĂĄ-Icardo M, MartĂ­nez-Calatayud J (2008) Crit Rev Anal Chem 38:118–130Ministerio de Medio Ambiente y Medio Rural y Marino. http://www.marm.es/ (accessed in September 2008)US Environmental Protection Agency. http://www.epa.gov/OGWWDW/contaminants (accessed in October 2008
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