RESUMO
Pulsed sounds are an interesting example of complex biological sounds, frequent in cetaceans' vocalizations. A two-group classification of these sounds is proposed: tonal or non-tonal. Through two simple mathematical models, it is shown that this classification can lead to better techniques for measuring the pulse rate. This classification is thus useful for improving measurement accuracy, but can also help in formulating hypotheses regarding mechanisms of sound production. This method of classification is applied to south Pacific blue whale vocalizations and it is found that the pulse rate corresponds to the fundamental frequency (not expressed in the spectrum) of the song. Thus, the hypothesis that the sound is produced by only one organ and then filtered by the body of the giant is reinforced.
RESUMO
BACKGROUND: The use of the desirability function approach combined with the response surface methodology (RSM), also called Desirability Optimization Methodology (DOM), has been successfully applied to solve medical, chemical, and technological questions. It is particularly efficient for the determination of the optimal conditions in natural or industrial processes involving different factors leading to the antagonist responses. OBJECTIVES: Surprisingly, DOM has never been applied to the research programs devoted to the study of plant responses to the complex environmental changes, and thus to biotechnological questions. MATERIALS AND METHODS: In this article, DOM is used to study the response of Datura stramonium hairy roots (HRs), obtained by genetic transformation with Agrobacterium rhizogenes A4 strain, subjected to the jasmonate treatments. RESULTS: Antagonist effects on the growth and tropane alkaloid biosynthesis are confirmed. With a limited number of experimental conditions, it is shown that 0.06 mM jasmonic acid (JA) applied for 24 h leads to an optimal compromise. Hyoscyamine levels increase by up to 290% after 24 h and this treatment does not significantly inhibit biomass growth. CONCLUSIONS: It is thus demonstrated that the use of DOM can efficiently - with a minimized number of replicates - leads to the optimization of the biotechnological processes.
RESUMO
The numerical simulation of acoustic waves in complex three-dimensional (3D) media is a key topic in many branches of science, from exploration geophysics to non-destructive testing and medical imaging. With the drastic increase in computing capabilities this field has dramatically grown in the last 20 years. However many 3D computations, especially at high frequency and/or long range, are still far beyond current reach and force researchers to resort to approximations, for example, by working in two dimensions (plane strain) or by using a paraxial approximation. This article presents and validates a numerical technique based on an axisymmetric formulation of a spectral finite-element method in the time domain for heterogeneous fluid-solid media. Taking advantage of axisymmetry enables the study of relevant 3D configurations at a very moderate computational cost. The axisymmetric spectral-element formulation is first introduced, and validation tests are then performed. A typical application of interest in ocean acoustics showing upslope propagation above a dipping viscoelastic ocean bottom is then presented. The method correctly models backscattered waves and explains the transmission losses discrepancies pointed out in F. B. Jensen, P. L. Nielsen, M. Zampolli, M. D. Collins, and W. L. Siegmann, Proceedings of the 8th International Conference on Theoretical and Computational Acoustics (ICTCA) (2007). Finally, a realistic application to a double seamount problem is considered.
