1,812 research outputs found

    Integrable models of galactic discs with double nuclei

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    We introduce a new class of 2-D mass models, whose potentials are of St\"ackel form in elliptic coordinates. Our model galaxies have two separate strong cusps that form double nuclei. The potential and surface density distributions are locally axisymmetric near the nuclei and become {\it highly} non-axisymmetric outside the nucleus. The surface density diverges toward the cuspy nuclei with the law Σr2\Sigma \propto r^{-2}. Our model is sustained by four general types of regular orbits: {\it butterfly}, {\it nucleuphilic banana}, {\it horseshoe} and {\it aligned loop} orbits. Horseshoes and nucleuphilic bananas support the existence of cuspy regions. Butterflies and aligned loops control the non-axisymmetric shape of outer regions. Without any need for central black holes, our distributed mass models resemble the nuclei of M31 and NGC4486B. It is also shown that the self-gravity of the stellar disc can prevent the double nucleus to collapse.Comment: 8 pages, accepted for publication in MNRA

    Processing and performance of compounds based on emulsion/solution SBRs

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    Solution and emulstion SBRs are both widely used in tire industry. But which method offers the industry the best solution

    Holographically description of Kerr-Bolt Black hole in terms of the warped conformal field theory

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    Recently it has been speculated that a set of diffeomorphisms exist which act non-trivially on the horizon of some black holes such as kerr and Kerr-Newman black hole. \cite{Haco:2018ske,Haco:2019ggi}. Using this symmetry in covariant phase space formalism one can obtains conserved charges as surface integrals on the horizon. Kerr-Bolt spacetime is well-known for its asymptotically topology and has been studied widely in recent years. In this work we are going to study Kerr-Bolt black hole and provide a holographically describtion of it in term of warped confromal field theory.Comment: 10 page

    Electronic, dielectric and optical properties of two dimensional and bulk ice: a multi-scale simulation study

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    The intercalated water into nanopores exhibits anomalous properties such as ultralow dielectric constant.~Multi-scale modeling and simulations are used to investigate the dielectric properties of various crystalline two-dimensional ices and bulk ices. Although, the structural properties of two-dimensional (2D-) ices have been extensively studied, much less is known about their electronic and optical properties. First, by using density functional theory (DFT) and density functional perturbation theory (DFPT), we calculate the key electronic, optical and dielectric properties of 2D-ices. Performing DFPT calculations, both the ionic and electronic contributions of the dielectric constant are computed. The in-plane electronic dielectric constant is found to be larger than the out-of-plane dielectric constant for all the studied 2D-ices. The in-plane dielectric constant of the electronic response is found to be isotropic for all the studied ices. Secondly, we determined the dipolar dielectric constant of 2D-ices using molecular dynamics simulations (MDS) at finite temperature. The total out-of-plane dielectric constant is found to be larger than 2 for all the studied 2D-ices. Within the framework of the random-phase approximation (RPA), the absorption energy ranges for 2D-ices are found to be in the ultraviolet spectra. For the comparison purposes, we also elucidate the electronic, dielectric and optical properties of four crystalline ices (ice VIII, ice XI, ice Ic and ice Ih) and bulk water

    Occurrence of parasites in selected fish species in Gandoman Lagoon, Iran

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    This study was carried out to investigate occurrence of parasite in selected cyprinid fish species in Gandoman Lagoon, in the vicinity of Gandoman City, Chaharmahal & Bakhtyari Province. A total of 90 fish specimens including Cyprinus carpio, Carassius auratus gibelio, Capoeta aculeata , C.damascina, Chondrostoma regium and Alburnus alburnus from Gandoman were examined during spring and summer 2007. Ten species of parasites were found, including Ichthyophthirius multifiliis, Trichodina sp. (Cilliophora), Myxobolus musayevi, Myxobolus sp. (Myxozoa), Dactylogyrus extensus, D.lenkorani (Monogenea), Diplostomum spathaceum, Tylodelphys clavata (Digenea). Argulus foliaceus and Lernea cyprinacea (Crustaceans). 77.7% of fishes were infected to parasites and 22.3 % did not show any infection. Chondrostoma regium and Alburnus alburnus are reported as new hosts for D. extensus
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