Gianantonio Guerrero

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A systematic study by HPLC was conducted to determine the content of chlorogenic acids in green coffee beans of the Variedad Colombia (Coffea arabica Caturra var. x Híbrido de Timor) and in other genotypes of interest of C. arabica, Coffea canephora, Híbrido de Timor, and the F1 offspring derived from the crossing Caturra x Híbrido de Timor. Comparisons(More)
We present non-linear mean-field αα dynamo simulations in spherical geometry with simplified profiles of kinetic α effect and shear. We take magnetic helicity evolution into account by solving a dynamical equation for the magnetic α effect. This gives a consistent description of the quenching mechanism in mean-field dynamo models. The main goal of this work(More)
Flux-dominated solar dynamo models, which have demonstrated to be quite successful in reproducing most of the observed features of the large scale solar magnetic cycle, generally produce an inappropriate latitudinal distribution of the toroidal magnetic fields, showing fields of large magnitude in polar regions where the radial shear has a maximum(More)
Many astrophysical bodies harbour magnetic fields that are thought to be sustained by a dynamo process. However, it has been argued that the production of large-scale magnetic fields by mean-field dynamo action is strongly suppressed at large magnetic Reynolds numbers owing to the conservation of magnetic helicity. This phenomenon is known as catastrophic(More)
We present the results of optical observations of the GRB 990510 field carried out at different epochs from Euro-pean Southern Observatory (ESO) telescopes. Deep observations , down to a limiting magnitude of about 27 and 24 in the Bessel–R and Gunn–I band, respectively, were obtained between May 16 and 18 from the ESO NTT–SUSI2 telescope and on May 20 from(More)
We present the results of optical observations of the GRB 990510 field carried out at different epochs from European Southern Observatory (ESO) telescopes. Deep observations, down to a limiting magnitude of about 27 and 24 in the Bessel–R and Gunn–I band, respectively , were obtained between May 16 and 18 from the ESO NTT–SUSI2 telescope and on May 20 from(More)
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