Stochastic gravitoelectromagnetic inflation

Gravitoelectromagnetic inflation was recently introduced to describe, in an unified manner, electromagnetic, gravitatory and inflaton fields in the early (accelerated) inflationary universe from a 5D vacuum state. In this Letter, we study a stochastic treatment for the gravitoelectromagnetic components AB=(Aμ,φ)$A_B=(A_{\mu },\phi )$, on cosmological scales. We focus our study on the seed magnetic fields on super-Hubble scales, which could play an important role in large scale structure formation of the universe.     

Whistle variability in South Atlantic spinner dolphins from the Fernando de Noronha archipelago off Brazil

A series of quali- and quantitative analyses were conducted to evaluate the variability of spinner dolphin whistles from the Fernando de Noronha Archipelago off Brazil. Nine variables were extracted from each whistle contour, and the whistle contours shapes were classified into the seven categories described in Driscoll (1995). The analysis showed mean beginning and ending frequencies values of 10.78 and 12.74 kHz, respectively. On average, whistle duration was relatively short, with mean values around 0.495 s (N=702). Comparative analyses were also conducted to investigate the relationship between the obtained results and those presented in previous studies. When comparing averages, the results of the study of Oswald et al.(2003) in the Tropical Eastern Pacific (TEP) presented less significant differences in relation to this study; only whistle duration differed significantly between both works. The results of multivariate classification tests also pointed TEP population as the closest related to the population studied here. The similarities between such disjunct populations might be attributed to a more recent isolation event (the closing of the Panama Isthmus) than the divergence that has driven North and South Atlantic populations apart.     

Thermodynamically consistent closure approximation for hard spheres systems

We present a new closure relation that is an extension of the Percus-Yevick approximation. In the proposed closure, we introduce an additional term and a mixing coefficient that can be determined by imposing a condition of thermodynamic self-consistency. Moreover, the mixing coefficient is calculated analytically within a linear approximation. In the case of a monodisperse system of hard spheres, we compare the results of our model to well-established thermodynamic expressions and also to the structural properties of fairly known closure approximations. In the second case, and using an equivalent scheme, the new closure relation is extended to the depletion potential between two large hard spheres immersed in a liquid of small hard spheres. In both cases, the results of our model are in good agreement with numerical simulations performed at intermediate concentrations.     

Parallel hybrid heuristics for the permutation flow shop problem

This paper addresses the Permutation Flowshop Problem with minimization of makespan, which is denoted by Fm|prmu|C _max. In the permutational scenario, the sequence of jobs has to remain the same in all machines. The Flowshop Problem (FSP) is known to be NP-hard when more than three machines are considered. Thus, for medium and large scale instances, high-quality heuristics are needed to find good solutions in reasonable time. We propose and analyse parallel hybrid search methods that fully use the computational power of current multi-core machines. The parallel methods combine a memetic algorithm (MA) and several iterated greedy algorithms (IG) running concurrently. Two test scenarios were included, with short and long CPU times. The tests were conducted on the set of benchmark instances introduced by Taillard (Eur. J. Oper. Res. 64:278?C285, 1993), commonly used to assess the performance of new methods. Results indicate that the use of the MA to manage a pool of solutions is highly effective, allowing the improvement of the best known upper bound for one of the instances.     

Energy decay to Timoshenko system with indefinite damping

We consider the classical Timoshenko system for vibrations of thin rods. The system has an indefinite damping mechanism, ie, it has a damping function a=a(x) possibly changing sign, present only in the equation for the vertical displacement. We shall prove that exponential stability depends on conditions regarding of the indefinite damping function a and a nice relationship between the coefficient of the system. Finally, we give some numerical result to verify our analytical results.     

A syzygetic approach to the smoothability of zero-dimensional schemes

We consider the question of which zero-dimensional schemes deform to a collection of distinct points; equivalently, we ask which Artinian k-algebras deform to a product of fields. We introduce a syzygetic invariant which sheds light on this question for zero-dimensional schemes of regularity two. This invariant imposes obstructions for smoothability in general, and it completely answers the question of smoothability for certain zero-dimensional schemes of low degree. The tools of this paper also lead to other results about Hilbert schemes of points, including a characterization of nonsmoothable zero-dimensional schemes of minimal degree in every embedding dimension d?4.     

GRASP heuristic with path-relinking for the multi-plant capacitated lot sizing problem

This paper addresses the independent multi-plant, multi-period, and multi-item capacitated lot sizing problem where transfers between the plants are allowed. This is an NP-hard combinatorial optimization problem and few solution methods have been proposed to solve it. We develop a GRASP (Greedy Randomized Adaptive Search Procedure) heuristic as well as a path-relinking intensification procedure to find cost-effective solutions for this problem. In addition, the proposed heuristics is used to solve some instances of the capacitated lot sizing problem with parallel machines. The results of the computational tests show that the proposed heuristics outperform other heuristics previously described in the literature. The results are confirmed by statistical tests.     

Use of isoelectric point and pH to evaluate the synthesis of a nanotubular aluminosilicate

To follow the synthesis of imogolite, transmission electron microscopy is needed. In this paper, the isoelectric point (IEP) and the aging pH are proposed as alternative methods. Two synthetic procedures were used (S-I and S-II), both involving a co-precipitation followed by an aging treatment where the aluminosilicate evolves from proto-imogolite (detected after the co-precipitation step), to imogolite; its formation is reached after 120 h (S-I) or 168 h (S-II) of aging, depending on the co-precipitation method used. In S-I the isoelectric point increases from 7.1 to 10.5, while in S-II it increases from 6.6 to 9.2 during the aging treatment. Additionally, a linear relationship between the IEP and the pH at different aging steps was found. That relationship may be used to follow the process of synthesis by simply measuring the pH, becoming an alternative to more complex methods.     

Evidence for resonance behaviour of A1 and A3 mesons coherently produced on nuclei

An analysis of about 60 000 events produced in the reaction π^?A → (π⁺π^?π^?)A on nine different nuclear targets A at 8.9, 12.9, and 15.1 GeV/c has been performed using the Illinois PWA program.In the A₁ region our “coherent” sample of events (which contains about 11% of incoherently produced events) is described by only four partial waves: the 1⁺S and 1⁺P amplitudes, which both show a peak, and the O^?S and O^?P waves, which are rather constant. We observed variations of both 1⁺S and 1⁺P phases relative to the O^?P phase by about 90° across the A₁ peak. This observation suggests the presence of resonant 1⁺ waves in the A₁ mass region (～1.1 GeV).In the A₃ region we observe that the 2^? state shows resonance behaviour and that fπ and ?π are two decays modes with amplitudes of opposite signs.     

Hydrogen transfer reactions catalyzed by neutral rhodium(I) Schiff base complexes

Summary Hydrogen transfer reactions from 2-propanol to acetophenone or cyclohexene are catalyzed by neutral rhodium(I) complexes of the type [Rh(COD)L] and [Rh₂(COD)₂L] (where L and L are Schiff base ligands and COD=cycloocta-1,5-diene). Some dependency of the catalytic activity on the electronic and steric properties of the ligands are discussed.