Ketene Thioacetals from α-Chloromercaptals

Excellent yields of ketene thioacetals are obtained from 2-(1-chloroalkyl)-1,3-dithiolanes or 2-(I-chloroalkyl)-1,3-dithianes.     

Computation of the separatrix of basins of attraction in a non-smooth dynamical system

This paper describes a new numerical method to compute the separatrix of the basins of attraction of coexisting attractors in a forced friction oscillator. Numerical results show that its intersection with a Poincaré section is a non-smooth curve.     

Salvatore Pincherle

Commemorazione letta davanti alla Classe di Scienze fisiche, matematiche e naturali della Reale Accademia Nazionale dei Lincei nell'adunanza del 5 dicembre 1937-XVI.     

Controllability of the discrete-spectrum Schrödinger equation driven by an external field

We prove approximate controllability of the bilinear Schrödinger equation in the case in which the uncontrolled Hamiltonian has discrete non-resonant spectrum. The results that are obtained apply both to bounded or unbounded domains and to the case in which the control potential is bounded or unbounded. The method relies on finite-dimensional techniques applied to the Galerkin approximations and permits, in addition, to get some controllability properties for the density matrix. Two examples are presented: the harmonic oscillator and the 3D well of potential, both controlled by suitable potentials.     

Study on sublimation of solid electrolyte (AgI)0.5‐(AgPO3)0.5 with Knudsen effusion mass spectrometry

Knudsen high‐temperature mass spectrometry was used to study the process of sublimation of a solid electrolyte (AgI)_0.5‐(AgPO₃)_0.5. Monoatomic iodine ions were found to be the dominant species in the electron ionization mass spectra below 600°C. With an increase in temperature, the relative content of phosphorus oxide ions, mainly [PO]⁺ and [P₄O₁₀]⁺, increased. Under further heating, we observed silver iodide and iodine dimer ions together with phosphorus dimer and tetramer ions and clusters [IPO₂]⁺, [IP₂]⁺, [I₃P]⁺. Using the experimental logarithmic dependencies of ion signal intensities versus the reciprocal absolute temperature of the effusion cell, the apparent sublimation enthalpies Δ_sH of the ions giving the most intense signals were estimated. Copyright © 2008 John Wiley & Sons, Ltd.     

New frontiers in computing and data analysis – the European perspectives

ABSTRACT

Nowadays, Europe is heavily engaged in the evolution of a new generation of high-performance computing (HPC), and new perspectives are looking at the emerging computational era called exascale. The presence of converging, domain-independent interests on Big Data among different communities, from Information Communication Technologies (ITC) to Life Sciences, Physics, Astrophysics, Space Sciences and many other fields, as well as the development of new skills, is leading to the establishment of specific collaborations with the aim of exploiting knowledge, capacities and research and innovation potential from different communities. The new program of Europe (named EuroHPC) is encouraging the sharing of these experiences and the cooperation between different entities like scientific research centers, small and medium-sized enterprises (SMEs) and private industries, for joint actions and the development of new skills in the Big Data and artificial intelligence (AI) domains. This program has two main pillars: ‘Supercomputing and Data Infrastructure Programme’ to deliver two world-class precursors of exascale supercomputers on 2020 and ‘Research and Innovation Programme’ on HPC to support the development of European supercomputing technology with the co-design of European exascale machines and to foster applications, skills development and a wider use of the new generation of computing systems. The co-design of these new systems, considering the big amount of data they need to handle with increasingly complexity, will also drive the development of a new generation of artificial intelligence techniques and visual analytics systems to underpin more accurate investigations. This paper is an analysis of the evolution of computing from a European perspective, looking at new generation systems and data analysis techniques in the era of Big Data, illustrating ideas with examples developed within the context of a specific physics field.     

Improved convergence estimates for the Schröder–Siegel problem

Annali di Matematica Pura ed Applicata (1923 -) - We reconsider the Schröder–Siegel problem of conjugating an analytic map in $$\mathbb {C}$$ in the neighborhood of a fixed point to its...