Search for sub-eV mass solar axions by the CERN Axion Solar Telescope with 3He buffer gas

The CERN Axion Solar Telescope (CAST) has extended its search for solar axions by using (3)He as a buffer gas. At T=1.8 K this allows for larger pressure settings and hence sensitivity to higher axion masses than our previous measurements with (4)He. With about 1 h of data taking at each of 252 different pressure settings we have scanned the axion mass range 0.39 eV?m(a)?0.64 eV. From the absence of excess x rays when the magnet was pointing to the Sun we set a typical upper limit on the axion-photon coupling of g(aγ)?2.3×10(-10) GeV(-1) at 95% C.L., the exact value depending on the pressure setting. Kim-Shifman-Vainshtein-Zakharov axions are excluded at the upper end of our mass range, the first time ever for any solar axion search. In the future we will extend our search to m(a)?1.15 eV, comfortably overlapping with cosmological hot dark matter bounds.     

On a Regularized Family of Models for Homogeneous Incompressible Two-Phase Flows

We consider a general family of regularized models for incompressible two-phase flows based on the Allen–Cahn formulation in \(n\) -dimensional compact Riemannian manifolds for \(n=2,3\) . The system we consider consists of a regularized family of Navier–Stokes equations (including the Navier–Stokes- \(\alpha \) -like model, the Leray- \(\alpha \) model, the modified Leray- \(\alpha \) model, the simplified Bardina model, the Navier–Stokes–Voight model, and the Navier–Stokes model) for the fluid velocity \(u\) suitably coupled with a convective Allen–Cahn equation for the order (phase) parameter \(\phi \) . We give a unified analysis of the entire three-parameter family of two-phase models using only abstract mapping properties of the principal dissipation and smoothing operators and then use assumptions about the specific form of the parameterizations, leading to specific models, only when necessary to obtain the sharpest results. We establish existence, stability, and regularity results and some results for singular perturbations, which as special cases include the inviscid limit of viscous models and the \(\alpha \rightarrow 0\) limit in \(\alpha \) models. Then we show the existence of a global attractor and exponential attractor for our general model and establish precise conditions under which each trajectory \(\left( u,\phi \right) \) converges to a single equilibrium by means of a Lojasiewicz–Simon inequality. We also derive new results on the existence of global and exponential attractors for the regularized family of Navier–Stokes equations and magnetohydrodynamics models that improve and complement the results of Holst et al. (J Nonlinear Sci 20(5):523–567, 2010). Finally, our analysis is applied to certain regularized Ericksen–Leslie models for the hydrodynamics of liquid crystals in \(n\) -dimensional compact Riemannian manifolds.     

A Possibilistic Approach of the Max-Product Bernstein Kind Operators

By analogy with the probabilistic approach of the classical Bernstein polynomials, in this paper firstly we give the proof for the uniform convergence of the nonlinear max-product Bernstein operator by using the theory of possibility. This new approach, which interprets the max-product Bernstein operator as a possibilistic expectation of a particular fuzzy variable having a possibilistic Bernoulli distribution, does not only offer a good justification for the max-product Bernstein operator, but also allows to extend the method to other discrete max-product Bernstein type operators.     

Ultra-high-speed liquid chromatography combined with mass spectrometry detection analytical methods for the determination of nitrosamine drug substance-related impurities

In the present study, five simple, feasible, and sensitive Ultra-high-speed liquid chromatography combined with mass spectrometry detection methods, using electrospray ionization are proposed. These methods were developed and validated for the determination of four different nitrosamine drug substance-related impurities—N-nitrosoacebutolol, N-nitrosobisoprolol, N-nitrosometoprolol, and N-nitrososotalol—in five beta blockers active pharmaceutical ingredients—acebutolol HCl, bisoprolol fumarate, metoprolol tartrate, metoprolol succinate, and sotalol HCl. The proposed methods were validated as per regulatory guidelines. Acquity HSS T3 (3.0 × 100 mm, 1.8 μm) column and formic acid 0.1% in water combined with methanol or acetonitrile were used for chromatographic separation in all methods. The limit of detection and the limit of quantification were found to be in the range of 0.02–1.2 and 2–20 parts per billion, respectively. The accuracy and precision of the five methods have been demonstrated in the working range of each one, giving values of recovery within the range of 64.1%–113.3%, and the regression coefficients (R) were found to be in the range of 0.9978–0.9999. These methods could be used for controlling nitrosamine drug substance-related impurities content for beta blockers drug substances batches manufactured at Moehs group.     

Synthesis and characterization of a new green‐emitting poly(phenylenevinylene) derivative containing alkylsilylphenyl pendant

A new type of processable green‐emissive polymer containing alkylsilylphenyl units was synthesized via Gilch polymerization. The resulting polymer was soluble in organic solvents and was spin‐cast to make a thin film. A light‐emitting diode was fabricated by the polymer being sandwiched between indium tin oxide and metal electrodes. A strong green emission at 524 nm was observed from the various device configurations made by the newly synthesized polymer. The polymer had a strong absorption band around 427 nm that was attributable to a π–π* transition of the conjugated segments of the polymer. A current–voltage–luminance curve showed typical rectifying diode characteristics. The polymer had a very high molecular weight (number‐average molecular weight = ∼300,000) with a polydispersity of about 3 and good thermal stability up to 400 °C. The brightness at 13 and 17 V was about 1000 and 5900 cd/m², respectively. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4185–4193, 2000     

Photoluminescence of single quantum wires and quantum dots

The results of a study into the photoluminescence spectra of a set of quantum dots based on GaAs enclosed in AlGaAs nanowires are presented. The steady state and time resolved spectra of photoluminescence under optical excitation both from an array of quantum wires/dots and a single quantum wire/dot have been measured. In the photoluminescence spectra of single quantum dots, emission lines of excitons, biexcitons and tritons have been found. The binding energy of the biexciton in the studied structures was deduced to be 8 meV.     

Temperature switch based on optical bistability

We have demonstrated a temperature switch based on an optically bistable device integrated with an optical fibre. The principle demonstrated here might lead to the development of new types of all-optical temperature sensors.     

Tangent cones and C1 regularity of definable sets

Let $X?{\mathbb{R}}^n$ be a connected locally closed set which is definable in an o-minimal structure. We prove that the following three statements are equivalent: (i) X is a $C^1$ manifold, (ii) the tangent cone and the paratangent cone of X coincide at every point in X, (iii) for every $x\in X$, the tangent cone of X at the point x is a k-dimensional linear subspace of ${\mathbb{R}}^n$ (k does not depend on x) varies continuously in x, and the density $\theta (X,x)<3/2$.