495 research outputs found

    Quasi-exactly solvable quartic: elementary integrals and asymptotics

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    We study elementary eigenfunctions y=p exp(h) of operators L(y)=y"+Py, where p, h and P are polynomials in one variable. For the case when h is an odd cubic polynomial, we found an interesting identity which is used to describe the spectral locus. We also establish some asymptotic properties of the QES spectral locus.Comment: 20 pages, 1 figure. Added Introduction and several references, corrected misprint

    <i>Bacillus anthracis</i> Siderophores

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    Iron is an essential for growth and reproduction of bacteria element. One of the ways of its acquisition by Bacillus anthracis is utilization of high-affinity chelating agents of iron ions - bacillibactin and petrobactin siderophores, extracting the iron from transferring and ferritin of a host cell. Bacillibactin and petrobactin functions are realized on different stages of B. anthracis growth in vivo, whereas petrobactin synthesis is also necessary for manifestation of microbe virulence. Awareness of siderophore biosynthesis pathways facilitates the development of medicines against anthrax, which can block them up. The review contains the data on the structure, genetics, and functions of B. anthracis siderophores

    Generalized Faddeev equations in the AGS form for deuteron stripping with explicit inclusion of target excitations and Coulomb interaction

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    Theoretical description of reactions in general, and the theory for (d,p)(d,p) reactions, in particular, needs to advance into the new century. Here deuteron stripping processes off a target nucleus consisting of A{A} nucleons are treated within the framework of the few-body integral equations theory. The generalized Faddeev equations in the AGS form, which take into account the target excitations, with realistic optical potentials provide the most advanced and complete description of the deuteron stripping. The main problem in practical application of such equations is the screening of the Coulomb potential, which works only for light nuclei. In this paper we present a new formulation of the Faddeev equations in the AGS form taking into account the target excitations with explicit inclusion of the Coulomb interaction. By projecting the (A+2)(A+2)-body operators onto target states, matrix three-body integral equations are derived which allow for the incorporation of the excited states of the target nucleons. Using the explicit equations for the partial Coulomb scattering wave functions in the momentum space we present the AGS equations in the Coulomb distorted wave representation without screening procedure. We also use the explicit expression for the off-shell two-body Coulomb scattering TT-matrix which is needed to calculate the effective potentials in the AGS equations. The integrals containing the off-shell Coulomb T-matrix are regularized to make the obtained equations suitable for calculations. For NNNN and nucleon-target nuclear interactions we assume the separable potentials what significantly simplifies solution of the AGS equations.Comment: 34 pages, 13 figure
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