Taste symmetry breaking at finite temperature

The breaking of the taste symmetry is studied in the temperature range between 140 MeV to 550 MeV. In order to investigate this violation we have calculated the screening masses of the various taste states fitting the exponential decay of the spatial correlators. The computation has been performed using dynamical N _f =2+1 gauge field configurations generated with the p4 staggered action along the Line of Constant Physics (LCP) defined by a pion mass m _π of approximately 220 MeV and the kaon mass m _K equals 500 MeV. For temperatures below the transition an agreement with the predictions of the staggered chiral perturbation theory has been found and no temperature effect can be observed on the taste violation. Above the transition the taste splitting still shows an $\mathcal{O}(a^{2})$ behavior but with a temperature-dependent slope. In addition to the analysis done for the pion multiplet we have performed an analogous computation for the light–strange and strange mesons and also looked at the scalar, vector and axial-vector channels to understand how the multiplets split at finite temperature. Finally the temperature dependence of the pion decay constant f _π is investigated to get further information regarding the chiral symmetry restoration.     

Sensitive determination of 3-methoxy-4-hydroxyphenylglycol (MHPG) in human plasma by HPLC with electrochemical detection

Summary This study deals with the development of a new HPLC method for the determination of 3-methoxy-4-hydroxyphenylglycol (MHPG), the main noradrenaline metabolite in human plasma. A Varian reversed-phase column (C₈; 250 mm×4.6 mm i.d.; 5 μm particles) was used as the stationary phase and an aqueous solution of citric acid, 1-octanesulfonic acid, EDTA, and methanol was used as the mobile phase. Coulometric electrochemical detection (ED) was used to obtain the highest sensitivity. Isolation of MHPG from plasma was accomplished by means of a new solid-phase extraction procedure after a protein precipitation step. The extraction yield of MHPG from plasma was very high (>97%). Linearity was observed in the 0.5–25 ng mL⁻¹ concentration range; the limit of detection was 0.2 ng mL⁻¹ and the limit of quantitation was 0.5 ng mL⁻¹. Repeatability (RSD,%) for plasma samples was found to be <3.2% and intermediate precision was <4.3%. The method was applied to the determination of MHPG in the plasma of healthy subjects under experimentally-induced psychological stress.     

Overcoming the boundary effects in surface spline interpolation

Surface spline interpolation when the domain is all of R^d isknown to converge much faster to the data function f than inthe case when the domain is the unit ball. This difference isunderstood to be due to boundary effects which, as will be shown,also affect the size of the surface spline's coefficients. Wepropose a modified form of surface spline interpolation which,to a great extent, overcomes these boundary effects. This modifiedsurface spline interpolant uses only the values of f at thegiven interpolation points.     

Optical Properties of M(II) Schiff-base Complexes Dispersed in Ethylene based Polymers

Summary: Several salicylaldiminate M(II) complexes of Nickel, Copper and Cobalt have been prepared and mixed with ethylene based polymers in order to prepare new composite materials with interesting morphological and optical properties by profiting of the presence of alkyl chains and push-pull substituents connected to the ligand structure. The phase dispersion behaviour of the binary films has been studied by scanning electron microscopy (SEM) and x-ray microanalysis, whereas the optical properties of the composite samples have been evaluated by UV-vis and fluorescence spectroscopy. The results in absorption have been analysed in terms of the anisotropy induced by the mechanical orientation of the polymer matrix and by the role of the metal centre according to the different strength of the complexes transition dipole moment. The luminescence behaviour have been discussed in terms of potential developments aimed at preparing polymeric supported Schiff base ligands for metal ions sensor applications.     

Synthesis and Spectroscopic Characterization of Thienopyrazine-Based Fluorophores for Application in Luminescent Solar Concentrators (LSCs)

Organic fluorophores have found broad application as emitters in luminescent solar concentrators (LSCs) for silicon photovoltaics. In particular, the preparation of organic conjugated systems with intense light-harvesting ability, emissions in the deep-red and NIR regions, and large Stokes shift values represent a very challenging undertaking. Here, we report a simple and easy way to prepare three symmetrical donor–acceptor–donor (DAD) organic-emitting materials based on a thienopyrazine core. The central core in the three dyes was modified with the introduction of aromatic substituents, aiming to affect their optical properties. The fluorophores were characterized by spectroscopic studies. In all cases, visible-NIR emissions with large Stokes shifts were found, highlighting these molecules as promising materials for the application in LSCs.     

An elementary proof of an equivalence theorem relevant in the theory of optimization

The authors give an elementary proof of an equivalence theorem of analysis which is often used in optimization theory. The theorem asserts that certain conditions are equivalent to weak convergence inL ₁. One is the Dunford-Pettis condition concerning absolute integrability. Two others are expressed in terms of Nagumo functions, and can be thought of as growth properties. The original proofs of the various parts of the theorem are scattered in different and specialized mathematical publications. The authors feel it useful to present here a straightforward proof of the various parts in terms of standard Lebesgue integration theory.     

Generalized 1/Z expansion for heteronuclear molecules

We have first studied empirical regularities in various series of heteronuclear diatomic molecules between the energy E, the total number of electrons N, the equilibrium distance R_e and Z? = (Z₁Z₂)^1/2 where Z₁e and Z₂e are the nuclear charges in the diatom. In particular, for various alkali halide series, R_e²|E|/N^5/3 is shown to correlate rather simply with Z?R_e³. Some theoretical basis is afforded by generalizing the 1/Z expansion used early by the writers in work on homonuclear diatomics. Finally, when Z₂/Z₁ → ∞, a model is presented which predicts a finite asymptotic bond length and this prediction is confronted with available experimental data for both heteronuclear diatoms and for the polyatomic series CH₄ to SnH₄.     

Local asymptotic stability for dissipative wave systems

We study the question of asymptotic stability, as time tends to infinity, of solutions of dissipative wave systems, governed by time-dependent nonlinear damping forces and by strongly nonlinear potential energies. This problem had been considered earlier for potential energies which arise from restoring forces, whereas here we allow as well for the effect of amplifying forces. Global asymptotic stability can then no longer be expected, and should be replaced by local stability. The conclusions are related to and supplement earlier work of Payne and Sattinger [7], who treated the nondissipative case, and of Hale [1], who showed the existence of connected global attractors.