On the solutions in the large of the two-dimensional flow of a nonviscous incompressible fluid

The Euler equations (1.1) for the motion of a nonviscous imcompressible fluid in a plane domain Ω are studied. Let E be the Banach space defined in (1.4), let the initial data v₀ belong to E, and let the external forces f(t) belong to L_loc¹(R; E). In Theorem 1.1 the strong continuity and the global boundedness of the (unique) solution v(t) are proved, and in Theorem 1.2 the strong-continuous dependence of v on the data v₀ and f is proved. In particular the vorticity rot v(t) is a continuous function in $\text{}\text{?}$gW, for every t ? R, if and only if this property holds for one value of t. In Theorem 1.3 some properties for the associated group of nonlinear operators S(t). are stated. Finally, in Theorem 1.4 a quite general sufficient condition is given on the data in order to get classical solutions.     

Complexation of Vinpocetine with Cyclodextrins in the Presence or Absence of Polymers. Binary and Ternary Complexes Preparation and Characterization

Inclusion complexation between -cyclodextrin (-CD),hydroxypropyl--cyclodextrin (HP--CD), water-solublepolymers (PVP and HPMC) and vinpocetine was studied in aqueous solution and in the solid state.Phase solubility studies were used to evaluate the complexation in aqueous solution at roomtemperature. Stability constants (K_c) of binary and ternary complexes were determined spectrophotometrically. Differential scanning calorimetry (DSC)was used to characterize kneaded, co-evaporated and lyophilised binary and ternary systems.The K_c values obtained were 70.14 M^-1 and 35.01 M^-1 for vinpocetine--CD and vinpocetine-HP--CD and increased in a range of 17% to 94%by addition of water-soluble polymers. Some preliminary evidences ofinclusion complexation were obtained from DSC suggesting that co-evaporated and lyophilised binary andternary systems were truly inclusion complexes.     

Crystal refinement and magnetic structure of KNi4(PO4)3: a novel example of three interacting magnetic sub-lattices

KNi(4)(PO(4))(3) has been synthesised following a method previously reported by some of us and studied on the basis of magnetization and neutron powder diffraction (NPD) data. Magnetization measurements suggest the coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) interactions: magnetization versus magnetic field curves present a remanent magnetization of around 2.15 micro(B) at T=2 K. The magnetic structure of the KNi(4)(PO(4))(3) has been determined at low temperature from the NPD data. These measurements show that there are three magnetic sub-lattices of Ni(2+) ions, which interact through common oxygen or phosphate groups, giving rise to FM and AFM couplings. The resulting interactions are FM in nature. Such a complex behaviour could provide an interesting model to analyse magnetic interactions in more condensed systems, such in mixed metal oxides.     

Crystal and magnetic structure of the system Li0.5+0.5xFe2.5-1.5xTixO4 (x=0.16, 0.44, and 0.72)

The influence of thermal treatment on the structure of lithium titanium ferrite spinels of general formula Li(0.5+0.5x)Fe(2.5-1.5x)Ti(x)O4 (x=0.16, 0.44, and 0.72) has been studied by X-ray and neutron diffraction and analysed by the Rietveld method. The results allow us to conclude the presence of an ordered phase (space group P4(3)32) at room temperature for the sample with x=0.16; this phase does not appear for the remaining compositions. The magnetic properties evidence a ferrimagnetic ordering in the structures when a random cation distribution (space group Fd3 m) is obtained. An exhaustive study carried out by neutron diffraction measurements on these samples shows a different behaviour when the titanium content is increased, concluding that the lower substituted phase (x=0.16) exhibits a Neel's collinear ferrimagnetic structure, with the higher substituted structures being noncollinear (x=0.44 and 0.72).     

Dynamic effects in inefficiency: Evidence from the Colombian banking sector

Firms face a continuous process of technological and environmental changes that requires them to make managerial decisions in a dynamic context. However, costs and constraints prevent firms from making instant adjustments towards optimal conditions and may cause inefficiency to persist in time. We propose a dynamic inefficiency specification that captures differences in the adjustment costs among firms and non-persistent effects of inefficiency heterogeneity. The model is fitted to a ten year sample of Colombian banks. The new specification improves model fit and have effects on efficiency estimations. Overall, Colombian banks present high inefficiency persistence but important differences between institutions are found. In particular, merged banks present low adjustment costs that allow them to recover rapidly efficiency losses derived from merging processes.     

Post processing of solution and flux for the nodal mimetic finite difference method

We develop and analyze a post processing technique for the family of low‐order mimetic discretizations based on vertex unknowns for the numerical treatment of diffusion problems on unstructured polygonal and polyhedral meshes. The post processing works in two steps. First, from the nodal degrees of freedom, we reconstruct an elemental‐based vector field that approximates the gradient of the exact solution. Second, we solve a local problem for each mesh vertex associated with a scheme degree of freedom to determine a post processed normal flux that is conservative and divergence preserving. Theoretical results and numerical experiments for two‐dimensional (2D) and 3D benchmark problems show optimal convergence rates. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 336–363, 2015     

A quasi-continuous observation of the α-transition of Fe1 + x S by Mössbauer line tracking

Mössbauer absorption line tracking methodology, under a constant velocity strategy, is used for a quasi-continuous observation of the $\upalpha $ -transition on slightly non stoichiometric Fe_1?+?x S alloy. To this end, two strategies were applied: an intelligent absorption line tracking with a control algorithm that uses the data measured in the previous region to establish the position of the next partial spectral range; and a predetermined line tracking in which temperature evolution of a partial spectral region of interest (ROI) is programmed. The latter uses results from the former, in order to achieve a quasi-continuous partial spectral observation. These experiments clearly demonstrate that line tracking allows a more efficient use of the radioactive source, as the effort is concentrated in a partial region of the spectra from which the desired information can be obtained.