7,331 research outputs found
Magnetic variability in the young solar analog KIC 10644253: Observations from the Kepler satellite and the HERMES spectrograph
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
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
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
A precise measurement of the neutron decay -asymmetry 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 , from which we determine the ratio of the
axial-vector to vector weak coupling of the nucleon .Comment: 5 pages, 2 figure
Complex regional pain syndrome 1 â the Swiss cohort study
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
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
Various new physics models predict a light CP-odd Higgs boson (labeled as
) and open up new decay modes for Z-boson, such as ,
and , 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 for
(), for and for , which
implies that the decays and 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
Recommended from our members
SEIS: Insight's Seismic Experiment for Internal Structure of Mars.
By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ⌠2500 at 1 Hz and ⌠200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ⌠3 at 40 â epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.Electronic supplementary materialThe online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users
Directed -in vitro- evolution of Precambrian and extant Rubiscos
Rubisco is an ancient, catalytically conserved yet slow enzyme, which plays a central role in the
biosphereâs 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
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
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):523â531Rial Otero R, Cancho Grande B, PĂ©rez Lamela C, Simal Gandara J, Aria Estevez M (2006) J Chromatogr Sci 44(9):539â542Aramendia MA, Borau V, Lafont F, Marinas JM, Moreno JM, Porras JM, Urbano FJ (2006) Food Chem 97(1):181â188Nuñez O, Moyano E, Galceran MT (2004) Anal Chim Acta 525(2):183â190Martinez Vidal JL, Belmonte Vega A, Sanchez Lopez FJ, Garrido Frenich AJ (2004) Chromatogr A 1050(2):179â184Lee XP, Kumazawa T, Fujishiro M, Hasegawa C, Arinobu T, Seno H, Sato K (2004) J Mass Spectrom 39(10):1147â1152De Almeida RM, Yonamine M (2007) J Chromatogr B 853(1â2):260â264De Souza D, Machado SAS (2006) Electroanalysis 18(9):862â872De Souza D, Da Silva MRC, Machado SAS (2006) Electroanalysis 18(23):2305â2313PicĂł Y, Rodriguez R, Manes J (2003) Trends Anal Chem 22(3):133â151Ishiwata T (2004) Bunseki Kagaku 53(8):863â864Carneiro MC, Puignou L, GalcerĂĄn MT (2000) Anal Chim Acta 408:263Luque M, Rios A, Valcarcel M (1998) Analyst 123(11):2383â2387Perez Ruiz T, MartĂnez Lozano C, Tomas V (1991) Int J Environ Anal Chem 44(4):243â252Perez Ruiz T, MartĂnez Lozano C, Tomas V (1991) Anal Chim Acta 244(1):99â104Townshend A (1990) Analyst 115:495â500LĂłpez Paz JL, CatalĂĄ Icardo M (2008) Anal Chim Acta 625:173â179PawlicovĂĄ Z, Sahuquillo I, CatalĂĄ Icardo M, GarcĂa Mateo JV, MartĂnez Calatayud J (2006) Anal Sci 22:29â34Albert GarcĂa JR, CatalĂĄ Icardo M, MartĂnez Calatayud J (2006) Talanta 69:608â614Tomlin CDS (1997) The pesticide manual, 11th edn.The British Crop Protection CouncilUKCatalĂĄ-Icardo M, MartĂnez-Calatayud J (2008) Crit Rev Anal Chem 38:118â130Ministerio 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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