1,041 research outputs found

    Bayesian analysis of magnetic island dynamics

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    We examine a first order differential equation with respect to time coming up in the description of magnetic islands in magnetically confined plasmas. The free parameters of this equation are obtained by employing Bayesian probability theory. Additionally a typical Bayesian change point is solved in the process of obtaining the data.Comment: 10 pages, 4 figures, submitted to be included in MaxEnt 2002 proceeding

    Cyclic pyrrole-imidazole polyamides targeted to the androgen response element

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    Hairpin pyrrole−imidazole (Py-Im) polyamides are a class of cell-permeable DNA-binding small molecules that can disrupt transcription factor−DNA binding and regulate endogenous gene expression. The covalent linkage of antiparallel Py-Im ring pairs with an γ-amino acid turn unit affords the classical hairpin Py-Im polyamide structure. Closing the hairpin with a second turn unit yields a cyclic polyamide, a lesser-studied architecture mainly attributable to synthetic inaccessibility. We have applied our methodology for solution-phase polyamide synthesis to cyclic polyamides with an improved high-yield cyclization step. Cyclic 8-ring Py-Im polyamides 1−3 target the DNA sequence 5′-WGWWCW-3′, which corresponds to the androgen response element (ARE) bound by the androgen receptor transcription factor to modulate gene expression. We find that cyclic Py-Im polyamides 1−3 bind DNA with exceptionally high affinities and regulate the expression of AR target genes in cell culture studies, from which we infer that the cycle is cell permeable

    Next generation hairpin polyamides with (R)-3,4-diaminobutyric acid turn unit

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    The characterization of a new class of pyrrole−imidazole hairpin polyamides with β-amino-γ-turn units for recognition of the DNA minor groove is reported. A library of eight hairpins containing (R)- and (S)-3,4-diaminobutyric acid (β-amino-γ-turn) has been synthesized, and the impact of the molecules on DNA-duplex stabilization was studied for comparison with the parent γ-aminobutyric acid (γ-turn) and standard (R)-2,4-diaminobutyric acid (α-amino-γ-turn)-linked eight-ring polyamides. For some, but not all, sequence compositions, melting temperature analyses have revealed that both enantiomeric forms of the β-amino-γ-turn increase the DNA-binding affinity of polyamides relative to the (R)-α-amino-γ-turn. The (R)-β-amine residue may be an attractive alternative for constructing hairpin polyamide conjugates. Biological assays have shown that (R)-β-amino-γ-turn hairpins are able to inhibit androgen receptor-mediated gene expression in cell culture similar to hairpins bearing the standard (R)-α-amino-γ-turn, from which we infer they are cell-permeable

    CPS Based Liquid Metal Divertor Target for EU-DEMO

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    AbstractPower exhaust is a key mission in the roadmap to the realization of a future fusion reactor. Among the different solutions, the use of liquid metals as plasma facing materials are of interest due to their potential increased lifetime. Several liquid metal limiters have been successfully tested in the Frascati Tokamak Upgrade over the last 10 years. Liquid materials such as lithium and tin have been investigated using capillary porous systems (CPSs), and their impact on plasma performance has been explored. From such experience, a liquid metal divertor (LMD) concept design, CPS-based, is here proposed. Tin has been preferred as plasma facing material. The proposed LMD would operate, in low evaporative regime, with matching heat exhausting capabilities to those of the baseline ITER-like divertor. Continuous refilling of the CPS is guaranteed with a reservoir at the back of the unit, where the metal is kept liquid through a gas heating circuit. The study has been carried out using ANSYS and the thermal results will be shown. All the design choices are compatible with the current materials and the constraints adopted for the DEMO W divertor. Using such configuration, thermal loads up to 20 MW/m2 are exhausted while keeping the surface temperature below 1250 °C. The design foresees values of pressure, temperature and flow rate of the water coolant in the same range expected for the W DEMO divertor, thus facilitating the integration of such solution in the current cassette design. Technological and practical aspects are addressed, i.e. tin corrosion and CPS wettability. Possible solutions to prevent tin corrosion, and its compatibility with structural materials, will be outlined

    Electron-correlation effects in appearance-potential spectra of Ni

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    Spin-resolved and temperature-dependent appearance-potential spectra of ferromagnetic Nickel are measured and analyzed theoretically. The Lander self-convolution model which relates the line shape to the unoccupied part of the local density of states turns out to be insufficient. Electron correlations and orbitally resolved transition-matrix elements are shown to be essential for a quantitative agreement between experiment and theory.Comment: LaTeX, 6 pages, 2 eps figures included, Phys. Rev. B (in press

    Water hardness salts on the effectiveness of the fire extinguishing properties of foam have been used for firefighting

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    Изучалось влияние солей жесткости воды на эффективность огнетушащих свойств пенообразующих составов. В результате проведенного исследования с УПН Майское ПО-6А3F и УПН Снежное ПО-6ТФ установлено, что с увеличением жесткости воды, устойчивость пены снижается. Ее устойчивость зависит от таких факторов, как жесткость воды и заряд активного иона поверхностно активного вещества. Установлено, что с увеличением жесткости воды, увеличивается время тушения пожара и расход огнетушащих средств, для наиболее эффективного пожаротушения рекомендуется использовать воду с УПН Снежное ПО-6ТФ.Studied the effect of water hardness salts on the effectiveness of the fire extinguishing properties of the foam. As a result of the study with UPN may PO-6A3F and UPN Snow PO-6TF found that with increasing water hardness, foam stability decreases. Its stability depends on factors such as water hardness and charge of the active ion of the surfactant. It is established that with increase of water hardness, increasing the extinguishing of the fire and amount of fire extinguishing, for the most effective fire-extinguishing it is recommended to use water with oil treatment IN a Snow-6ТФ
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