An efficient and scalable block parallel algorithm of Neville elimination as a tool for the CMB maps problem

This paper analyses the performance of several versions of a block parallel algorithm in order to apply Neville elimination in a distributed memory parallel computer. Neville elimination is a procedure to transform a square matrix A into an upper triangular one. This analysis must take into account the algorithm behaviour as far as execution time, efficiency and scalability are concerned. Special attention has been paid to the study of the scalability of the algorithms trying to establish the relationship existing between the size of the block and the performance obtained in this metric. It is important to emphasize the high efficiency achieved in the studied cases and that the experimental results confirm the theoretical approximation. Therefore, we have obtained a high predicting ability tool of analysis. Finally, we will present the elimination of Neville as an efficient tool in detecting point sources in cosmic microwave background maps.     

A New Approach to the Intensity of the Secondary Transition of the Benzene Chromophore with-CH3,-OH,-OCH3, Substituents

Since the beginning of the UV absorption spectroscopy, the intensity of the secondary transition of the benzene chromophore in organic derivatives has been a puzzling challenge. The well known vector model has led to some qualitative evaluation of intensity, but accuracy is very low, and sometimes leads to no less than 50% or 100% error. ^1–8 It is designed for very weak perturbations only, as in methylbenzenes. But, even in that latter case, it is not completely satisfactory. Nevertheless, that model is very easy to use; it allows to determine the sensitive positions around the benzene nucleus: those which could enhance or quench intensity for a given pattern of substitution. On that ground it has been of much help for qualitative evaluations. With SCF methods and CI calculations, evaluation of transition moments for several benzene derivatives has been possible on a firmer ground. In fact, such an approach is useful mainly from a theoretical point of view, when accuracy is not the first aim, for some choosen molecules at the same time, since the involvement of computation is far from being negligible, and since the method is not part of the ones that are of common use in organic chemistry ^9,10 (for a recent example on oscillator strength calculations of π systems see:¹¹). In other words, it is not perfectly valuable on a large scale and routine approach and, from that point of view, UV spectroscopy of benzene derivatives appeared sometimes, from 1965 till now, as being in a cul-de-sac, although it was under thorough examination (for example: 12–30). Until recently ab initio calculations have failed to reach a fit with experiment better than 1 eV for the spectrum of the benzene molecule^31–32)     

Residual‐based stabilization of the finite element approximation to the acoustic perturbation equations for low Mach number aeroacoustics

The acoustic perturbation equations (APE) are suitable to predict aerodynamic noise in the presence of a non‐uniform mean flow. As for any hybrid computational aeroacoustics approach, a first computational fluid dynamics simulation is carried out from which the mean flow characteristics and acoustic sources are obtained. In a second step, the APE are solved to get the acoustic pressure and particle velocity fields. However, resorting to the finite element method (FEM) for that purpose is not straightforward. Whereas mixed finite elements satisfying an appropriate inf–sup compatibility condition can be built in the case of no mean flow, that is, for the standard wave equation in mixed form, these are difficult to implement and their good performance is yet to be checked for more complex wave operators. As a consequence, strong simplifying assumptions are usually considered when solving the APE with FEM. It is possible to avoid them by resorting to stabilized formulations. In this work, a residual‐based stabilized FEM is presented for the APE at low Mach numbers, which allows one to deal with the APE convective and reaction terms in its full extent. The key of the approach resides in the design of the matrix of stabilization parameters. The performance of the formulation and the contributions of the different terms in the equations are tested for an acoustic pulse propagating in sheared‐solenoidal mean flow, and for the aeolian tone generated by flow past a two‐dimensional cylinder. Copyright © 2016 John Wiley & Sons, Ltd.     

Cyclobutane-based peptides/terpyridine conjugates: Their use in metal catalysis and as functional organogelators

Two new conjugates, hcptpyDP and hcptpyTP, of a terpyridine derivative incorporating artificial peptide moieties, have been synthesized and their use in the preparation of metal catalysts and organogelators has been investigated. Ru(II) complexes derived from these ligands showed electrochemical behavior and activity as catalysts in the epoxidation of olefins similar to that of Beller's catalyst. As organogelators, these conjugates were able to gelate a variety of solvents, from toluene to methanol, with satisfactory mgc (minimum gelation concentration) values. The presence of 4′-(4-carboxy)phenylterpyridine (hcptpy) moiety allows tuning the gelling properties and also influences the supramolecular self-assembling mode to produce chiral aggregates with respect to parent peptides DP and TP. In the case of the conjugates, π?π interactions provided by the aromatic moieties cooperate with inter-molecular hydrogen bonding between NH and CO in the amide groups. Further properties of peptide/terpyridine conjugates are under investigation in view of future applications.     

Synthesis of N,N'-Disubstituted α,ω-Alkanediamines,Precursors of Linear bisDithiocarbamates

Linear bis dithiocarbamates are conveniently obtained from symmetrical disubstituted α,ω-alkanediamines whose preparation is reported.     

Non-linear parallel solver for detecting point sources in CMB maps using Bayesian techniques

In this work we present a suitable computational tool to deal with large matrices and solve systems of non-linear equations. This technique is applied to a very interesting problem: the detection and flux estimation of point sources in Cosmic Microwave Background (CMB) maps, which allows a good determination of CMB primordial fluctuations and leads to a better knowledge of the chemistry at the early stages of the Universe. The method uses previous information about the statistical properties of the sources, so that this knowledge is incorporated in a Bayesian scheme. Simulations show that our approach allows the detection of more sources than previous non-Bayesian techniques, with a small computation time.