Phase separation near half-filling point in superconducting compounds

We present the model of superconducting ceramics using the single band extended Hubbard Hamiltonian. We investigate the simultaneous presence of antiferromagnetism (AF) and d-wave superconductivity (SC) in the coherent potential (CP) approximation applied to the on-site Coulomb repulsion $U$. We consider the hopping interaction, $\Delta t$, the inter-site charge-charge interaction, $V$, (creating SC), and the single site Hund's type exchange interaction, $F_{in}$, (creating AF). The influence of these interactions on the separation of superconducting and antiferromagnetic phases near the half-filling point is investigated. Results are compared with the experimental data for YBaCuO and NdCeCuO compounds.Comment: 4 pages, 4 figure

Alternative equation of motion approach to the single-impurity Anderson model

Solving the single-impurity Anderson model (SIAM) is a basic problem of solid state physics. The SIAM model is very important, at present it is also used for systems with quantum impurities, e.g. semiconductor quantum dots and molecular transistors. Its main application is in the scheme of dynamical mean field theory (DMFT) describing strong correlation electron systems. To solve the SIAM problem we use the equation of motion (EOM) Green function approach. In this report we present the novel EOM approximation in which we differentiate the Green function over both time variables. This differs from the commonly used EOM solution by Appelbaum, Penn and Lacroix where the authors take time derivative only over primary time variable. After extending calculations to higher order Green functions we find the new approximate dynamical solution of SIAM. The results are compared with the solutions to the SIAM problem at intermediate Coulomb repulsion U such as the Modified Iterative Perturbation Theory. Our approach is suitable for describing quantum dots.Comment: 6 pages, 3 figure

Free wake analysis of helicopter rotor flow fields using a coupled voricity embedding/fractional step method

A hybrid CFD (Computational Fluid Dynamics) method combining a potential-based Vorticity Embedding method with an Euler solver is presented and validated for isolated rotor flows First, a formulation of Vorticity Embedding is developed and validated for Cartesian grids This formulation is utilized together with simple lifting lines to represent an isolated rotor in hover The results for an isolated rotor are then compared with experiment The method is then hybridized by coupling the Vorticity Embedding grid containing the rotor to a region containing a ground plane where a standard finite difference Euler solver is utilized Initial results from this hybrid scheme are presented including a demonstration of the code\u27s potential to calculate the ground vortex roll-up generated by a rotor in ground effect in the presence of a cross-win

Invisible Charm Exotica

One possible interpretation of two narrow $\Omega^0_c$ states reported by the LHCb Collaboration at CERN in 2017 is that they are pentaquarks belonging to a $\overline{\boldsymbol{15}}$ exotic SU(3) representation, as predicted by the Chiral Quark--Soliton Model. If so, there must exist a number of other exotic states since the model predicts three different $\overline{\boldsymbol{15}}$ multiplets of heavy baryons. We show, that depending on the soliton spin $J$, these states are either very narrow or very broad. This explains why they might have escaped experimental observation. Furthermore, we show that the lightest members of these multiplets are stable against two body strong decays.Comment: 11 pages, 3 figures, v2 accepted in Phys. Rev.

Guerny – Les Aulnaies

Si depuis 2015 des fouilles archéologiques programmées subaquatiques sont menées dans l’Epte par le Club d’archéologie subaquatique du Val-d’Oise (Casavo) et le Centre de recherche archéologique du Vexin français (Cravf), la campagne de 2018 était la première d’une autorisation triennale 2018-2020. Les investigations des années antérieures avaient mis en avant la présence d’une structure au centre de la rivière, composée de plusieurs alignements de pieux et d’un apport de silex et de calcaire..

Guerny – Les Aulnaies

Depuis 2015, le club d’archéologie subaquatique du Val-d’Oise (Casavo) et le Centre de recherches archéologiques du Vexin français (Cravf) fouillent en collaboration une nouvelle zone de la rivière Epte. En effet les prospections thématiques effectuées en 2014 ont permis de définir un secteur comportant d’importants aménagements anthropiques. Cette zone a fait l’objet d’approfondissements avec une fouille archéologique subaquatique programmée en 2015 où une méthodologie adaptée a été mise en ..