4,132 research outputs found

    Observability of atomic line features in strong magnetic fields

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    The physical properties of atoms in superstrong magnetic fields, characteristic of neutron stars, and the possibility of detecting magnetically strongly shifted atomic lines in the spectra of magnetized X-ray pulsars are discussed. It is suggested that it is recommendable to look for magnetically strongly shifted Fe 26 Lyman lines in rotating neutron stars of not too high luminosity using spectrometers working in the energy range 10 - 20 keV, with sensitivities to minus 4 power photons per sq cm and second, and resolution E/delta E approx. 10-100

    Estimating Drift Parameters in a Fractional Ornstein Uhlenbeck Process with Periodic Mean

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    We construct a least squares estimator for the drift parameters of a fractional Ornstein Uhlenbeck process with periodic mean function and long range dependence. For this estimator we prove consistency and asymptotic normality. In contrast to the classical fractional Ornstein Uhlenbeck process without periodic mean function the rate of convergence is slower depending on the Hurst parameter HH, namely n1−Hn^{1-H}

    Post-Roman to Medieval landscape transformations in the Erlauf Valley, Austria (5th–11th centuries AD) a Mick Aston Grant report

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    This is the final version. Available from the publisher website via the link in this record.Society for Medival Archaeolog

    Unification in Abelian Semigroups

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    Unification in equational theories, i.e. solving of equations in varieties, is a basic operation in Computational Logic, in Artificial Intelligence (AI) and in many applications of Computer Science. In particular the unification of terms in the presence of an associative and commutative f unction, i.e. solving of equations in Abelian Semigroups, turned out to be of practical relevance for Term Rewriting Systems, Automated Theorem Provers and many AI-programming languages. The observation that unification under associativity and commutativity reduces to the solution of certain linear diophantine equations is the basis for a complete and minimal unification algorithm. The set of most general unifiers is closely related to the notion of a basis for the linear solution space of these equations. These results are extended to unification in free term algebras combined with Abelian Semigroups

    Decoupling of Mechanical Structures with Piezoceramic Stacks

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    A review of the development and realisation of an adaptive interface for decoupling of two mechanical systems is presented. An approach is utilized to design an adaptronical system by means of rapid-prototyping on the basis of a simulation. The method includes the calculation of the dynamic behaviour of the mechanical structure with the help of FEM. The FE-model of the mechanical structure is reduced and embedded as modal state-space-model with the numerical simulation software MATLAB/ Simulink. Actuators and sensors are integrated into the mechanical structure. Based on the resulting dynamical behaviour of the mechanical structure an adaptive control algorithm for the decoupling of structural vibrations is developed. Experimental tests are performed to confirm and to update the simulations. The hardware-in-the-loop-simulation is performed with the commercial rapid-prototyping dSpace-system. This procedure allows the development and the evaluation of more complex adaptive mechanical structures

    Clinical and functional characterisation of a novel TNFRSF1A c.605T > A/V173D cleavage site mutation associated with tumour necrosis factor receptor-associated periodic fever syndrome (TRAPS), cardiovascular complications and excellent response to etanercept treatment.

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    Objectives: To study the clinical outcome, treatment response, T-cell subsets and functional consequences of a novel tumour necrosis factor (TNF) receptor type 1 (TNFRSF1A) mutation affecting the receptor cleavage site. Methods: Patients with symptoms suggestive of tumour necrosis factor receptor-associated periodic syndrome (TRAPS) and 22 healthy controls (HC) were screened for mutations in the TNFRSF1A gene. Soluble TNFRSF1A and inflammatory cytokines were measured by ELISAs. TNFRSF1A shedding was examined by stimulation of peripheral blood mononuclear cells (PBMCs) with phorbol 12-myristate 13-acetate followed by flow cytometric analysis (FACS). Apoptosis of PBMCs was studied by stimulation with TNFa in the presence of cycloheximide and annexin V staining. T cell phenotypes were monitored by FACS. Results: TNFRSF1A sequencing disclosed a novel V173D/ p.Val202Asp substitution encoded by exon 6 in one family, the c.194–14G.A splice variant in another and the R92Q/p.Arg121Gln substitution in two families. Cardiovascular complications (lethal heart attack and peripheral arterial thrombosis) developed in two V173D patients. Subsequent etanercept treatment of the V173D carriers was highly effective over an 18-month follow-up period. Serum TNFRSF1A levels did not differ between TRAPS patients and HC, while TNFRSF1A cleavage from monocytes was significantly reduced in V173D and R92Q patients. TNFa-induced apoptosis of PBMCs and T-cell senescence were comparable between V173D patients and HC. Conclusions: The TNFRSF1A V173D cleavage site mutation may be associated with an increased risk for cardiovascular complications and shows a strong response to etanercept. T-cell senescence does not seem to have a pathogenetic role in affected patients
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