556 research outputs found

    The first view of δ Scuti and γ Doradus stars with the TESS mission

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    We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 and 2 of the TESS mission. We utilize the 2-min cadence TESS data for a sample of 117 stars to classify their behaviour regarding variability and place them in the Hertzsprung-Russell diagram using Gaia DR2 data. Included within our sample are the eponymous members of two pulsator classes, γ Doradus and SX Phoenicis. Our sample of pulsating intermediate-mass stars observed by TESS also allows us to confront theoretical models of pulsation driving in the classical instability strip for the first time and show that mixing processes in the outer envelope play an important role. We derive an empirical estimate of 74 per cent for the relative amplitude suppression factor as a result of the redder TESS passband compared to the Kepler mission using a pulsating eclipsing binary system. Furthermore, our sample contains many high-frequency pulsators, allowing us to probe the frequency variability of hot young δ Scuti stars, which were lacking in the Kepler mission data set, and identify promising targets for future asteroseismic modelling. The TESS data also allow us to refine the stellar parameters of SX Phoenicis, which is believed to be a blue straggler.Fil: Antoci, Victoria. Stellar Astrophysics Centre; DinamarcaFil: Cunha, M. S.. Universidad de Porto; PortugalFil: Bowman, D. M.. Institute of Astronomy; BélgicaFil: Murphy, S. J.. Stellar Astrophysics Centre; Dinamarca. University of Sydney; AustraliaFil: Kurtz, D. W.. University of Central Lancashire; Reino UnidoFil: Bedding, T. R.. Stellar Astrophysics Centre; Dinamarca. University of Sydney; AustraliaFil: Borre, C. C.. Stellar Astrophysics Centre; DinamarcaFil: Christophe, S.. Universite de Paris I Pantheon - Sorbonne; Francia. Centre National de la Recherche Scientifique. Observatoire de Paris; FranciaFil: Daszynska Daszkiewicz, J.. Instytut Astronomiczny; PoloniaFil: Fox Machado, L.. Universidad Nacional Autónoma de México; MéxicoFil: García Hernández, A.. Universidad de Granada; EspañaFil: Ghasemi, Hamed. Institute For Advanced Studies In Basic Sciences; IránFil: Handberg, R.. Stellar Astrophysics Centre; DinamarcaFil: Hansen, Ted H.. Stellar Astrophysics Centre; DinamarcaFil: Hasanzadeh, A.. University Of Zanjan; IránFil: Houdek, G.. Stellar Astrophysics Centre; DinamarcaFil: Johnston, C.. Katholikie Universiteit Leuven; BélgicaFil: Justesen, A. B.. Stellar Astrophysics Centre; DinamarcaFil: Kahraman Alicavus, F.. Nicolaus Copernicus Astronomical Center Of The Polish Academy Of Sciences; PoloniaFil: Kotysz, K.. Instytut Astronomiczny, Uniwersytet Wrocławski; PoloniaFil: Latham, D.. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Matthews, J. M.. University of British Columbia; CanadáFil: Mønster, J.. Stellar Astrophysics Centre; DinamarcaFil: Niemczura, E.. Uniwersytet Wrocławski; PoloniaFil: Paunzen, E.. Masaryk University; República ChecaFil: Sánchez Arias, Julieta Paz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Pigulski, A.. Uniwersytet Wrocławski; PoloniaFil: Pepper, J.. Lehigh University; Estados UnidosFil: Richey Yowell, T.. Lehigh University; Estados UnidosFil: Safari, H.. University of Zanjan; Irá

    Coupling dynamics of a geared multibody system supported by Elastohydrodynamic lubricated cylindrical joints

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    A comprehensive computational methodology to study the coupling dynamics of a geared multibody system supported by ElastoHydroDynamic (EHD) lubricated cylindrical joints is proposed throughout this work. The geared multibody system is described by using the Absolute-Coordinate-Based (ACB) method that combines the Natural Coordinate Formulation (NCF) describing rigid bodies and the Absolute Nodal Coordinate Formulation (ANCF) characterizing the flexible bodies. Based on the finite-short bearing approach, the EHD lubrication condition for the cylindrical joints supporting the geared system is considered here. The lubrication forces developed at the cylindrical joints are obtained by solving the Reynolds’ equation via the finite difference method. For the evaluation of the normal contact forces of gear pair along the Line Of Action (LOA), the time-varying mesh stiffness, mesh damping and Static Transmission Error (STE) are utilized. The time-varying mesh stiffness is calculated by using the Chaari’s methodology. The forces of sliding friction along the Off-Line-Of-Action (OLOA) are computed by using the Coulomb friction models with a time-varying coefficient of friction under the EHD lubrication condition of gear teeth. Finally, two numerical examples of application are presented to demonstrate and validate the proposed methodology.National Natural Science Foundations of China under Grant 11290151, 11221202 and 11002022, Beijing Higher Education Young Elite Teacher Project under Grant YETP1201

    Biology, Fishery, Conservation and Management of Indian Ocean Tuna Fisheries

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    The focus of the study is to explore the recent trend of the world tuna fishery with special reference to the Indian Ocean tuna fisheries and its conservation and sustainable management. In the Indian Ocean, tuna catches have increased rapidly from about 179959 t in 1980 to about 832246 t in 1995. They have continued to increase up to 2005; the catch that year was 1201465 t, forming about 26% of the world catch. Since 2006 onwards there has been a decline in the volume of catches and in 2008 the catch was only 913625 t. The Principal species caught in the Indian Ocean are skipjack and yellowfin. Western Indian Ocean contributed 78.2% and eastern Indian Ocean 21.8% of the total tuna production from the Indian Ocean. The Indian Ocean stock is currently overfished and IOTC has made some recommendations for management regulations aimed at sustaining the tuna stock. Fishing operations can cause ecological impacts of different types: by catches, damage of the habitat, mortalities caused by lost or discarded gear, pollution, generation of marine debris, etc. Periodic reassessment of the tuna potential is also required with adequate inputs from exploratory surveys as well as commercial landings and this may prevent any unsustainable trends in the development of the tuna fishing industry in the Indian Ocean

    Planetary bearing defect detection in a commercial helicopter main gearbox with vibration and acoustic emission

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Helicopter gearboxes significantly differ from other transmission types and exhibit unique behaviors that reduce the effectiveness of traditional fault diagnostics methods. In addition, due to lack of redundancy, helicopter transmission failure can lead to catastrophic accidents. Bearing faults in helicopter gearboxes are difficult to discriminate due to the low signal to noise ratio (SNR) in the presence of gear vibration. In addition, the vibration response from the planet gear bearings must be transmitted via a time-varying path through the ring gear to externally mounted accelerometers, which cause yet further bearing vibration signal suppression. This research programme has resulted in the successful proof of concept of a broadband wireless transmission sensor that incorporates power scavenging whilst operating within a helicopter gearbox. In addition, this paper investigates the application of signal separation techniques in detection of bearing faults within the epicyclic module of a large helicopter (CS-29) main gearbox using vibration and Acoustic Emissions (AE). It compares their effectiveness for various operating conditions. Three signal processing techniques including an adaptive filter, spectral kurtosis and envelope analysis, were combined for this investigation. In addition, this research discusses the feasibility of using AE for helicopter gearbox monitoring

    Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells

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    The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT's voltage-sensing properties elicited by calcimycin or H2O2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the 'thinness ratio' and the 'cobalt-calcein' technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca(2+) levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H2O2-induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient

    Investigation of Atomic Level Patterns in Protein—Small Ligand Interactions

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    BACKGROUND: Shape complementarity and non-covalent interactions are believed to drive protein-ligand interaction. To date protein-protein, protein-DNA, and protein-RNA interactions were systematically investigated, which is in contrast to interactions with small ligands. We investigate the role of covalent and non-covalent bonds in protein-small ligand interactions using a comprehensive dataset of 2,320 complexes. METHODOLOGY AND PRINCIPAL FINDINGS: We show that protein-ligand interactions are governed by different forces for different ligand types, i.e., protein-organic compound interactions are governed by hydrogen bonds, van der Waals contacts, and covalent bonds; protein-metal ion interactions are dominated by electrostatic force and coordination bonds; protein-anion interactions are established with electrostatic force, hydrogen bonds, and van der Waals contacts; and protein-inorganic cluster interactions are driven by coordination bonds. We extracted several frequently occurring atomic-level patterns concerning these interactions. For instance, 73% of investigated covalent bonds were summarized with just three patterns in which bonds are formed between thiol of Cys and carbon or sulfur atoms of ligands, and nitrogen of Lys and carbon of ligands. Similar patterns were found for the coordination bonds. Hydrogen bonds occur in 67% of protein-organic compound complexes and 66% of them are formed between NH- group of protein residues and oxygen atom of ligands. We quantify relative abundance of specific interaction types and discuss their characteristic features. The extracted protein-organic compound patterns are shown to complement and improve a geometric approach for prediction of binding sites. CONCLUSIONS AND SIGNIFICANCE: We show that for a given type (group) of ligands and type of the interaction force, majority of protein-ligand interactions are repetitive and could be summarized with several simple atomic-level patterns. We summarize and analyze 10 frequently occurring interaction patterns that cover 56% of all considered complexes and we show a practical application for the patterns that concerns interactions with organic compounds

    Alterations in voltage-sensing of the mitochondrial permeability transition pore in ANT1-deficient cells

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    The probability of mitochondrial permeability transition (mPT) pore opening is inversely related to the magnitude of the proton electrochemical gradient. The module conferring sensitivity of the pore to this gradient has not been identified. We investigated mPT's voltage-sensing properties elicited by calcimycin or H2O2 in human fibroblasts exhibiting partial or complete lack of ANT1 and in C2C12 myotubes with knocked-down ANT1 expression. mPT onset was assessed by measuring in situ mitochondrial volume using the 'thinness ratio' and the 'cobalt-calcein' technique. De-energization hastened calcimycin-induced swelling in control and partially-expressing ANT1 fibroblasts, but not in cells lacking ANT1, despite greater losses of mitochondrial membrane potential. Matrix Ca(2+) levels measured by X-rhod-1 or mitochondrially-targeted ratiometric biosensor 4mtD3cpv, or ADP-ATP exchange rates did not differ among cell types. ANT1-null fibroblasts were also resistant to H2O2-induced mitochondrial swelling. Permeabilized C2C12 myotubes with knocked-down ANT1 exhibited higher calcium uptake capacity and voltage-thresholds of mPT opening inferred from cytochrome c release, but intact cells showed no differences in calcimycin-induced onset of mPT, irrespective of energization and ANT1 expression, albeit the number of cells undergoing mPT increased less significantly upon chemically-induced hypoxia than control cells. We conclude that ANT1 confers sensitivity of the pore to the electrochemical gradient

    European guideline on IgG4-related digestive disease – UEG and SGF evidence-based recommendations

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    The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6–0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2–4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added

    Membrane-mediated interactions

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    Interactions mediated by the cell membrane between inclusions, such as membrane proteins or antimicrobial peptides, play important roles in their biological activity. They also constitute a fascinating challenge for physicists, since they test the boundaries of our understanding of self-assembled lipid membranes, which are remarkable examples of two-dimensional complex fluids. Inclusions can couple to various degrees of freedom of the membrane, resulting in different types of interactions. In this chapter, we review the membrane-mediated interactions that arise from direct constraints imposed by inclusions on the shape of the membrane. These effects are generic and do not depend on specific chemical interactions. Hence, they can be studied using coarse-grained soft matter descriptions. We deal with long-range membrane-mediated interactions due to the constraints imposed by inclusions on membrane curvature and on its fluctuations. We also discuss the shorter-range interactions that arise from the constraints on membrane thickness imposed by inclusions presenting a hydrophobic mismatch with the membrane.Comment: 38 pages, 10 figures, pre-submission version. In: Bassereau P., Sens P. (eds) Physics of Biological Membranes. Springer, Cha
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