Aspects of macroscopic quantum tunnelling in small Josephson junctions

Summary We study the effect of temperature on the lifetime of the resonant macroscopic quantum tunnelling voltage state. In view of experiments we consider a merit factor in order to balance between measuring extremely small signals of longer duration or larger signals of shorter duration.     

Electron traps in GaS

Measurements performed on n-GaS by means of the space-charge limited current method indicate the presence of a deep trap for electrons, at 0.57 eV from the conduction band and with a density of about 2.3 × 10¹³cm^?3. Another deeper trap at 0.63 eV and with a density of 6 × 10¹²cm^?3 is probably also present. The results seem to confirm the validity of a new direct method of analysis. Traps are tentatively attributed to compensated sulphur vacancies.     

Trapping levels in PbI2

A first investigation on trapping levels in PbI₂, performed by the Thermally Stimulated Current (TSC) technique, is presented. Three hole trapping centers are evidenced at 0.12, 0.29 and 0.59 eV above the valence band, with densities ranging between 8 × 10¹⁴ and 5 × 10¹⁶ cm^?3 and capture cross-sections between 8 × 10^?21 and 3 × 10^?17 cm². The center at 0.59 eV is likely responsible for the relatively short trapping time in PbI₂, as determined with nuclear techniques. By using a particular method, the behaviour of hole drift mobility along the layers as a function of temperature is determined for the first time. Finally, the presence of a spurious peak, not sensitive to irradiation, is reported and discussed.     

Nonexistence of invariant graphs in all supercritical energy levels of mechanical Lagrangians in T 2

Let (T², g) be a smooth Riemannian structure in the torus T². We show that given ε > 0 and any C^∞ function U : T² → ℝ there exists a C¹ function U_ε with Lipschitz derivatives that is ε-C⁰ close to U for which there are no continuous invariant graphs in any supercritical energy level of the mechanical Lagrangian L_ε : TT² → ℝ given by . We also show that given n ∈ ℕ, the set of C^∞ potentials U : T² → ℝ for which there are no continuous invariant graphs in any supercritical energy level E ≤ n of is C⁰ dense in the set of C^∞ functions. Partially supported by CNPq, FAPERJ-Cientistas do nosso estado.     

The Walden cycle revisited: a computational study of competitive ring closure to alpha- and beta-lactones

The text-book Walden cycle which interconverts the stereochemical configurations of chlorosuccinic and malic acids involves a beta-lactone intermediate in preference to an alpha-lactone intermediate because the O(nuc) C Cl angle in the transition structure for the former (174 degrees) is more favourable than that for the latter (139 degrees), as determined by PCM(epsilon = 78.4)/B3LYP/6-31+G* calculations; the smaller ring-strain energy of the beta-lactone contributes little to the reactivity difference.     

Clustering dynamics in a class of normalised generalised gamma dependent priors

Normalised generalised gamma processes are random probability measures that induce nonparametric prior distributions widely used in Bayesian statistics, particularly for mixture modelling. We construct a class of dependent normalised generalised gamma priors induced by a stationary population model of Moran type, which exploits a generalised Pólya urn scheme associated with the prior. We study the asymptotic scaling for the dynamics of the number of clusters in the sample, which in turn provides a dynamic measure of diversity in the underlying population. The limit is formalised to be a positive non-stationary diffusion process which falls outside well-known families, with unbounded drift and an entrance boundary at the origin. We also introduce a new class of stationary positive diffusions, whose invariant measures are explicit and have power law tails, which approximate weakly the scaling limit.     

Introduction to the special issue for SIMAI 2016

This paper discusses the computation of real \(\mathtt {Z}\)-eigenvalues and \(\mathtt {H}\)-eigenvalues of nonsymmetric tensors. A generic nonsymmetric tensor has finitely many Z-eigenvalues, while there may be infinitely many ones for special tensors. The number of \(\mathtt {H}\)-eigenvalues is finite for all tensors. We propose Lasserre type semidefinite relaxation methods for computing such eigenvalues. For every tensor that has finitely many real \(\mathtt {Z}\)-eigenvalues, we can compute all of them; each of them can be computed by solving a finite sequence of semidefinite relaxations. For every tensor, we can compute all its real \(\mathtt {H}\)-eigenvalues; each of them can be computed by solving a finite sequence of semidefinite relaxations.     

Multiplexed therapeutic drug monitoring of antipsychotics in dried plasma spots by LC‐MS/MS

In this work, a convenient method for the therapeutic monitoring of seven common antipsychotic drugs in “dried plasma spot” samples has been developed. It is based on the liquid chromatography tandem mass spectrometry technique, operating in multiple reaction monitoring mode, and a straightforward procedure for the simultaneous extraction of all antipsychotics in a single step, with high extraction yield. The method was fully validated with proper accuracy, precision, selectivity and sensitivity, for all the drugs. Limits of quantification were 0.12, 1.09, 1.46, 1.47, 5.70, 1.32, 1.33 µg/L for haloperidol, aripiprazole, olanzapine, quetiapine, clozapine, risperidone, and paliperidone, respectively. Accuracy, intra‐ and interday precision values were <10% for all drugs at all concentration levels examined. The method was tested in the analysis of 30 plasma samples from real patients for each drug. The proposed analytical approach, by combining practical and logistical advantages of microsampling with liquid chromatography tandem mass spectrometry analytical performance, could offer an ideal strategy for accurate and timely therapeutic drug monitoring of antipsychotic drugs in most clinical settings, even in remote centers and/or in out‐patient settings, bringing so many potential improvements in psychiatric patient care.