8,108 research outputs found

    Photospheric activity, rotation, and star-planet interaction of the planet-hosting star CoRoT-6

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    The CoRoT satellite has recently discovered a hot Jupiter that transits across the disc of a F9V star called CoRoT-6 with a period of 8.886 days. We model the photospheric activity of the star and use the maps of the active regions to study stellar differential rotation and the star-planet interaction. We apply a maximum entropy spot model to fit the optical modulation as observed by CoRoT during a uninterrupted interval of about 140 days. Photospheric active regions are assumed to consist of spots and faculae in a fixed proportion with solar-like contrasts. Individual active regions have lifetimes up to 30-40 days. Most of them form and decay within five active longitudes whose different migration rates are attributed to the stellar differential rotation for which a lower limit of \Delta \Omega / \Omega = 0.12 \pm 0.02 is obtained. Several active regions show a maximum of activity at a longitude lagging the subplanetary point by about 200 degrees with the probability of a chance occurrence being smaller than 1 percent. Our spot modelling indicates that the photospheric activity of CoRoT-6 could be partially modulated by some kind of star-planet magnetic interaction, while an interaction related to tides is highly unlikely because of the weakness of the tidal force.Comment: 9 pages, 7 figures, accepted to Astronomy & Astrophysic

    Design for Low-Cost Country Sourcing: Motivation, Basic Principles and Design Guidelines

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    Organised by: Cranfield UniversityNot every product can be successfully sourced in low-cost countries. Disadvantageous cost structures or extremely complex workpiece designs are the most frequent reasons for failures. A design that has been tailored to low-cost country sourcing offers the possibility of increasing potentials while reducing risks and costs at the same time. The wbk Institute of Production Science at the Universität Karlsruhe (TH) developed a new approach which ensures that the product design meets the requirements of the supplier. This paper identifies the factors influencing the design, deduces basic principles and illustrates guidelines for an adapted product design.Mori Seiki – The Machine Tool Compan

    Event generator to construct cross sections for the multiphonon excitation of a set of collective vibrational modes

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    The construction of differential cross sections as a function of excitation energy for systems with a collection of low- and high-lying intrinsic vibrational modes has been attempted in the past. A prescription is proposed that simplifies the implementation of such calculation schemes with a remarkable reduction in computational time.Comment: 6 pages, 3 figures, to be published in Phys. Rev.

    Population of dipole states via isoscalar probes: the splitting of pygmy dipole resonance in 124^{124}Sn}

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    Inelastic α\alpha-scattering excitation cross sections are calculated for electric dipole excitations in 124^{124}Sn based on the transition densities obtained from the relativistic quasiparticle time-blocking approximation (RQTBA) in the framework of a semiclassical model. The calculation provides the missing link to directly compare the results from the microscopic RQTBA calculations to recent experimental data measured via the (α,αγ)(\alpha ,\alpha '\gamma) reaction, which show a structural splitting of the low-lying E1 strength often denoted as pygmy dipole resonance (PDR). The experimentally observed splitting is reproduced by the cross section calculations, which allows to draw conclusion on the structure of the PDR.Comment: 6 pages, 7 figures; accepted in Phys. Rev C as Rapid Communicatio

    Mass Formula for a Stationary Axisymmetric Configuration and the Physical Realization of the Kerr Metric

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    We analyse the expression for the mass of a stationary axisymmetric configuration in general relativity obtained in our previous work [1]. From the generality of our formula and its incompatibility with the corresponding expression in Kerr space-time we argue that a stationary equilibrium distribution of a real matter cannot be a source of the Kerr metric.Comment: RevTex, 5 pages, no figure

    Microscopic description of Coulomb and nuclear excitation of multiphonon states in 40^{40}Ca + 40^{40}Ca collisions

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    We calculate the inelastic scattering cross sections to populate one- and two-phonon states in heavy ion collisions with both Coulomb and nuclear excitations. Starting from a microscopic approach based on RPA, we go beyond it in order to treat anharmonicities and non-linear terms in the exciting field. These anharmonicities and non-linearities are shown to have important effects on the cross sections both in the low energy part of the spectrum and in the energy region of the Double Giant Quadrupole Resonance. By properly introducing an optical potential the inelastic cross section is calculated semiclassically by integrating the excitation probability over all impact parameters. A satisfactory agreement with the experimental results is obtained.Comment: 20 pages, 2 figures, revtex, to be published in Phys. Rev.

    A condition-specific codon optimization approach for improved heterologous gene expression in Saccharomyces cerevisiae

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    All authors are with the Department of Chemical Engineering, The University of Texas at Austin, 200 E Dean Keeton St. Stop C0400, Austin, TX 78712, USA -- Hal S. Alper is with the Institute for Cellular and Molecular Biology, The University of Texas at Austin, 2500 Speedway Avenue, Austin, TX 78712, USA -- Amanda M. Lanza Current Address: Bristol-Myers Squibb, Biologics Development, 35 South Street, Hopkinton, MA 01748, USABackground: Heterologous gene expression is an important tool for synthetic biology that enables metabolic engineering and the production of non-natural biologics in a variety of host organisms. The translational efficiency of heterologous genes can often be improved by optimizing synonymous codon usage to better match the host organism. However, traditional approaches for optimization neglect to take into account many factors known to influence synonymous codon distributions. Results: Here we define an alternative approach for codon optimization that utilizes systems level information and codon context for the condition under which heterologous genes are being expressed. Furthermore, we utilize a probabilistic algorithm to generate multiple variants of a given gene. We demonstrate improved translational efficiency using this condition-specific codon optimization approach with two heterologous genes, the fluorescent protein-encoding eGFP and the catechol 1,2-dioxygenase gene CatA, expressed in S. cerevisiae. For the latter case, optimization for stationary phase production resulted in nearly 2.9-fold improvements over commercial gene optimization algorithms. Conclusions: Codon optimization is now often a standard tool for protein expression, and while a variety of tools and approaches have been developed, they do not guarantee improved performance for all hosts of applications. Here, we suggest an alternative method for condition-specific codon optimization and demonstrate its utility in Saccharomyces cerevisiae as a proof of concept. However, this technique should be applicable to any organism for which gene expression data can be generated and is thus of potential interest for a variety of applications in metabolic and cellular engineering.Chemical EngineeringInstitute for Cellular and Molecular [email protected]

    Transparency in Global Production Networks: Improving Disruption Management by Increased Information Exchange

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    Modern companies operate in global production networks. The operational performance of production networks is hampered by disrupting events. Digitalization and the horizontal interlinkage of production networks may increase information exchange and lead to more transparency. It is propagated as being an enabler for a faster identification and reaction to disruptions. This paper presents a metamodeling approach that maps disruptions as systematic parameter variations and analyzes their impact on the performance of production networks under different level of information exchange. The method aims for the determination of cause-effect relationships and contributes to the determination of the appropriate level of information exchange in production networks

    Neurofibromatosis type I: Case report

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    We present a case of neurofibromatosis type 1 (NF-1) discussing how cutaneous manifestations of disorders or  syndromes can be difficult to identify, especially when they are present since birth, present also in a  percentage of normal population, and especially when these are isolated findings, not accompanied by other  clinical relevant signs or symptoms. It is well known that NF-1 is a rather heterogeneous condition, with different degrees of expression and including cutaneous manifestations. Although there are some life  threatening complications clearly associated, for most patients the primary concern and main clinical impact remains the disfigurement caused by the presence and growth of cutaneous-dermal neurofibromas. These lesions can be underestimated especially in the impact on quality of life and sequelae that can cause if abnormally large and not removed. We present a clinical history spanning several years, before managing to properly diagnose our patient with neurofibromatosis type 1 and treat the relevant skin manifestation causing significant deformity and quality of life consequences

    Smouldering onset of advanced mediastinal tumor in an adolescent boy: case report

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    An adolescent boy came at our observation with bilateral flaccid paralysis at both legs, cough, fecal and urinary incontinence. First symptoms started 6 months before, were initially mild and rather aspecific. There was incomplete information available from former diagnostic imaging and histologic assessment. We describe and discuss the subsequent diagnostic flow driving to the final diagnosis of spindle cell mediastinal carcinoma, its clinical management and outcome. Hopefully, sharing our lesson learnt may rise awareness around this rare tumor in adolescent population, in order to better anticipate diagnosis and improve its outcome
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