Joaquín Ramírez

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Bivalve nacre is a brick-wall-patterned biocomposite of aragonite platelets surrounded by organic matter. SEM-electron back scatter diffraction analysis of nacre of the bivalve family Pteriidae reveals that early aragonite crystals grow with their c-axes oriented perpendicular to the growth surface but have their a- and b-axes disoriented. With the(More)
Magnetism in pre-MS intermediate-mass stars and the fossil field hypothesis Abstract. Today, one of the greatest challenges concerning the Ap/Bp stars is to understand the origin of their slow rotation and their magnetic fields. The favoured hypothesis for the latter is the fossil field, which implies that the magnetic fields subsist throughout the(More)
Forest fire risk assessment is an important task for forest fire management and planning. This paper presents current work on the definition and implementation of forest fire risk assessment models in the Wildfire Analyst TM software with the purpose of providing support and increased value in risk assessment. Three models are presented based on the concept(More)
In this paper, the occurrence of synchronization in pairs of weakly nonlinear self-sustained oscillators that interact via Huygens' coupling, i.e., a suspended rigid bar, is treated. In the analysis, a generalized version of the classical Huygens' experiment of synchronization of two coupled pendulum clocks is considered, in which the clocks are replaced by(More)
From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 146233 (18 Sco) and HD 190771. Assuming that the observed variability of polari-metric signal is controlled by stellar rotation, we establish the rotation periods of our targets, with(More)
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