Periodically kicked hard oscillators

A model of a hard oscillator with analytic solution is presented. Its behavior under periodic kicking, for which a closed form stroboscopic map can be obtained, is studied. It is shown that the general structure of such an oscillator includes four distinct regions; the outer two regions correspond to very small or very large amplitude of the external force and match the corresponding regions in soft oscillators (invertible degree one and degree zero circle maps, respectively). There are two new regions for intermediate amplitude of the forcing. Region 3 corresponds to moderate high forcing, and is intrinsic to hard oscillators; it is characterized by discontinuous circle maps with a flat segment. Region 2 (low moderate forcing) has a certain resemblance to a similar region in soft oscillators (noninvertible degree one circle maps); however, the limit set of the dynamics in this region is not a circle, but a branched manifold, obtained as the tangent union of a circle and an interval; the topological structure of this object is generated by the finite size of the repelling set, and is therefore also intrinsic to hard oscillators.     

Regular and extremal solutions for difference equations with generalized phi-Laplacian

Non-oscillatory solutions for second-order difference equations with generalized phi-Laplacian are studied. Solutions are classified according to the asymptotic behaviour as regular or extremal solutions. Their existence and possible coexistence are investigated as well. In particular, the existence of infinitely many extremal solutions for equations with the discrete mean curvature operator is proved by means of an iterative method. This paper is completed by examples and some open problems.     

Tautomerisation of 2‐Substituted Pyridines to N‐Heterocyclic Carbene Ligands Induced by the 16 e− Unsaturated [TpMe2IrIII(C6H5)2] Moiety

The complex [Tp^Me2Ir(C₆H₅)₂(N₂)] reacts with several 2‐substituted pyridines to generate N‐heterocyclic carbenes resulting from a formal 1,2‐hydrogen shift from C₆ to N. In this paper we provide a detailed report of the scope and the mechanistic aspects (both experimental and theoretical) of the tautomerisation of 2‐substituted pyridines.     

Identification and assay of carbohydrates in olive drupes by cesium attachment electrospray tandem mass spectrometry (ESI-MS/MS)

Identification and assay of sugars in olive drupes during their ripening phase is evaluated by tandem mass spectrometry. Recent achievements have shown that the quality of an extra virgin olive oil can be directly correlated to the ripening degree of the drupes that is likely linked to their saccharides content. An innovation in this peculiar food chain is now proposed that considers a high throughput assessment of the carbohydrate content by a recently introduced protocol based on the gas-phase chemistry of sugar-cesium adducts by ESI-MS/MS. Copyright ? 2012 John Wiley & Sons, Ltd.     

A parallel solver for adaptive finite element discretizations

A parallel solver for the adaptive finite element analysis is presented. The primary aim of this work has been to establish an efficient parallel computational procedure which requires only local computations to update the solution of the system of equations arising from the finite element discretization after a local mesh-adaptation step. For this reason a set of algorithms has been developed (two-level domain decomposition, recursive hierarchical mesh-refinement, selective solution-update of linear systems of equations) which operate upon general and easily available partitioning, meshing and linear systems solving algorithms. AMS subject classification 15A23, 65N50, 65N60     

The dipole approach in the lon-interaction chromatography of zwitterions— Use of a potential approximation to obtain a simplified retention equation

Summary In ion-interaction chromatography (IIC) the zwitterionic analyte is believed to interact with the stationary phase potential as a result of its electrical dipole, and to compete with the ion-interaction reagent (IIR) for available inner layer sites. The most reliable set of literature data relating to the retention behavior of zwitterions in IIC has been used for successful testing of a high surface-potential approximation which enables the fitting of retention data without detailed information about the physical and chemical properties of the mobile phase. This approach can explain quantitatively, very simply, the retention behavior of zwitterions in IIC.     

Feasibility of oak leaves as monitor for airborne pollution

The present paper confirms that evergreen oak leaves (Ouercus ilex) are a reliable biological monitor for pollution originating from vehicular traffic. By treating of experimental data statistically a simple model was obtained which explains pollution levels in terms of vehicular density and particulate resuspension effects. An extensive list of current literature in this field is also included.