Nonsimplicity of certain universal C^*-algebras

Given n≥2" role="presentation">n≥2, zij∈T" role="presentation">zij∈T such that zij=z¯ji" role="presentation">zij=z¯ji for 1≤i,j≤n" role="presentation">1≤i,j≤n and zii=1" role="presentation">zii=1 for 1≤i≤n" role="presentation">1≤i≤n, and integers p1,…,pn≥1" role="presentation">p1,…,pn≥1, we show that the universal C*" role="presentation">C∗-algebra generated by unitaries u1,…,un" role="presentation">u1,…,un such that uipiujpj=zijujpjuipi" role="presentation">upiiupjj=zijupjjupii for 1≤i,j≤n" role="presentation">1≤i,j≤n is not simple if at least one exponent pi" role="presentation">pi is at least two. We indicate how the method of proof by “working with various quotients” can be used to establish nonsimplicity of universal C*" role="presentation">C∗-algebras in other cases.Article / Letter to editorMathematisch Instituu

Growth of CaF2 buffer on Si using low energy cluster beam deposition technique and study of its properties

International audienc

Nonsimplicity of certain universal C^*-algebras

Given n≥2" role="presentation">n≥2, zij∈T" role="presentation">zij∈T such that zij=z¯ji" role="presentation">zij=z¯ji for 1≤i,j≤n" role="presentation">1≤i,j≤n and zii=1" role="presentation">zii=1 for 1≤i≤n" role="presentation">1≤i≤n, and integers p1,…,pn≥1" role="presentation">p1,…,pn≥1, we show that the universal C*" role="presentation">C∗-algebra generated by unitaries u1,…,un" role="presentation">u1,…,un such that uipiujpj=zijujpjuipi" role="presentation">upiiupjj=zijupjjupii for 1≤i,j≤n" role="presentation">1≤i,j≤n is not simple if at least one exponent pi" role="presentation">pi is at least two. We indicate how the method of proof by “working with various quotients” can be used to establish nonsimplicity of universal C*" role="presentation">C∗-algebras in other cases.Analysis and Stochastic

Noncommutative quantum mechanics and Bohm's ontological interpretation

We carry out an investigation into the possibility of developing a Bohmian interpretation based on the continuous motion of point particles for noncommutative quantum mechanics. The conditions for such an interpretation to be consistent are determined, and the implications of its adoption for noncommutativity are discussed. A Bohmian analysis of the noncommutative harmonic oscillator is carried out in detail. By studying the particle motion in the oscillator orbits, we show that small-scale physics can have influence at large scales, something similar to the IR-UV mixing

Electrocatalytic Reduction of Bromothiophenes on Gold and Silver Electrodes: an Example of Synergism in Electrocatalysis

The reductive cleavage of C\u2013Br bonds on silver electrodes can be regarded as an ideal model of dissociative electron transfer (DET) in electrocatalytic conditions, modulated by many factors, among which the molecular structure is of particular relevance. A detailed mechanistic study based on a large set of compounds with different molecular structures allowed us a full rationalization of the process for the case of aryl bromides in acetonitrile. [1] Now we are extending this research to heteroaromatic halides, in which the heteroatom not only makes the aromatic ring asymmetric from the perspective of the electron density but also can have its own specific interactions with the electrode surface, in addition to those of the halide ions. [2] As a first approach, we have selected the mono-, di-, tri- and tetra-bromothiophene series, plus a series of substituted bromothiophenes together with the corresponding bromobenzenes as benchmarks, investigating (by CV, supported by EIS in selected cases) the electrochemical reduction of the whole family: (i) on glassy carbon, GC, assumed as a non-catalytic reference electrode accounting for intrinsic reactivity; (ii) on the highly catalytic silver electrode; (iii) on gold electrode, showing in former halide cases lower catalytic effects than silver but having the highest affinity for the sulphur atom in the thiophene ring. While the results on GC and on Ag are fully consistent with the formerly studied aryl bromide case on the same two electrodes [1] the catalytic effects of Au appear to be neatly modulated by the relative position of the Br leaving group with respect to the sulphur atom. This feature is quite evident and reproducible in the whole series (including polysubstituted cases provided by our organic partner group), and points to the S atom acting as an asymmetrically anchoring group for the molecule on the Au surface. [1] S. Arnaboldi, A. Gennaro, A.A. Isse, P.R. Mussini (2015) Electrochimica Acta, 158, 427-436 [2] S. Arnaboldi, A. Bonetti, E. Giussani, P.R. Mussini, T. Benincori, S. Rizzo, A.A. Isse, A. Gennaro (2014) Electrochemistry Communications, 38, 100-10

Olive phenology as a sensitive indicator of future climatic warming in the Mediterranean

Experimental and modelling work suggests a strong dependence of olive flowering date on spring temperatures. Since airborne pollen concentrations reflect the flowering phenology of olive populations within a radius of 50 km, they may be a sensitive regional indicator of climatic warming. We assessed this potential sensitivity with phenology models fitted to flowering dates inferred from maximum airborne pollen data. Of four models tested, a thermal time model gave the best fit for Montpellier, France, and was the most effective at the regional scale, providing reasonable predictions for 10 sites in the western Mediterranean. This model was forced with replicated future temperature simulations for the western Mediterranean from a coupled ocean-atmosphere general circulation model (GCM). The GCM temperatures rose by 4·5 °C between 1990 and 2099 with a 1% per year increase in greenhouse gases, and modelled flowering date advanced at a rate of 6·2 d per °C. The results indicated that this long-term regional trend in phenology might be statistically significant as early as 2030, but with marked spatial variation in magnitude, with the calculated flowering date between the 1990s and 2030s advancing by 3–23 d. Future monitoring of airborne olive pollen may therefore provide an early biological indicator of climatic warming in the Mediterranean

High Altitude test of RPCs for the ARGO-YBJ experiment

A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and time resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met