22,675 research outputs found

    Electrostatic contribution to DNA condensation - application of 'energy minimization' in a simple model in strong Coulomb coupling regime

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    Bending of DNA from a straight rod to a circular form in presence of any of the mono-, di-, tri- or tetravalent counterions has been simulated in strong Coulomb coupling environment employing a previously developed energy minimization simulation technique. The inherent characteristics of the simulation technique allow monitoring the required electrostatic contribution to the bending. The curvature of the bending has been found to play crucial roles in facilitating electrostatic attractive potential energy. The total electrostatic potential energy has been found to decrease with bending which indicates that bending a straight DNA to a circular form or to a toroidal form in presence of neutralizing counterions is energetically favorable and practically is a spontaneous phenomenon

    Chiral odd GPDs in transverse and longitudinal impact parameter spaces

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    We investigate the chiral odd generalized parton distributions (GPDs) for non-zero skewness ζ\zeta in transverse and longitudinal position spaces by taking Fourier transform with respect to the transverse and longitudinal momentum transfer respectively. We present overlap formulas for the chiral-odd GPDs in terms of light-front wave functions (LFWFs) of the proton both in the ERBL and DGLAP regions. We calculate them in a field theory inspired model of a relativistic spin 1/2 composite state with the correct correlation between the different LFWFs in Fock space, namely that of the quantum fluctuations of an electron in a generalized form of QED. We show the spin-orbit correlation effect of the two-particle LFWF as well as the correlation between the constituent spin and the transverse spin of the target.Comment: 1 figure and references added, typos corrected. version to appear in Phys.Rev.

    Reanalyzing the upper limit on the tensor-to-scalar perturbation ratio r_T in a quartic potential inflationary model

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    We study the polynomial chaotic inflation model with a single scalar field in a double well quartic potential which has recently been shown to be consistent with Planck data. In particular, we study the effects of lifting the degeneracy between the two vacua on the inflationary observables, i.e. spectral index n_s and tensor-to-scalar perturbation ratio r_T. We find that removing the degeneracy allows the model to satisfy the upper limit constraints on r_T from Planck data, provided the field starts near the local maximum. We also calculate the scalar power spectrum and non-Gaussianity parameter f_NL for the primordial scalar perturbations in this model.Comment: 7 pages, 7 figures; v2: discussion added, submitted to Phys. Lett. B; v3: published versio

    Synthesis of elastomers for use with liquid fluorine Quarterly letter report, 1 Sep. - 30 Nov. 1968

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    Phosphines as initiators of polymerization of hexafluorobutyne-

    Ultrapure glass optical waveguide development in microgravity by the sol-gel process

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    Multicomponent, homogeneous, noncrystalline oxide gels can be prepared by the sol-gel process and these gels are promising starting materials for melting glasses in the space environment. The sol-gel process referred to here is based on the polymerization reaction of alkoxysilane with other metal alkoxy compounds or suitable metal salts. Many of the alkoxysilanes or other metal alkoxides are liquids and thus can be purified by distillation. The use of gels offers several advantages such as high purity and lower melting times and temperatures. The sol-gel process is studied for utilization in the preparation of multicomponent ultrapure glass batches for subsequent containerless melting of the batches in space to prepare glass blanks for optical waveguides

    Synthesis of elastomers for use with liquid fluorine Final report

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    Synthesis and chemical properties of elastomeric polymers resistant to effects of fluorine, oxygen difluoride, nitrogen tetroxide, and similar agent

    Synthesis of elastomers for use with liquid fluorine Annual interim report

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    Elastomer synthesis for copolymerization with liquid fluorin
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