En esta tesis hemos estudiado una muestra de seis estrellas tipo Delta Scuti pertenecientes al cúmulo de las Pléyades observadas por medio de la red STEPHI a través de varias campañas multisitio, de las cuales dos fueron realizadas durante el desarrollo del presente trabajo. Dicha muestra consta de V650 Tau, V647 Tau, V534 Tau, V624 Tau, HD 23628 y

We present the first results of an observational project aimed at producing a database of nearby face-on spiral galaxies in the optical. The project is being run at the IAC-80 telescope in Tenerife. This first sample is made of from R and I images of NGC 428, 864, 2146, 2273, 2541, 2967, 4618, 4654, 6217, and 6643. Overall geometrical parameters

We explored the potential for use of the contractile proteins, actin and myosin, as biosensors of solutions containing mercury ions. We demonstrate that the reaction of HgCl2 with myosin rapidly inhibits actin-activated myosin ATPase activity. Mercuric ions inhibit the in vitro analog of contraction, namely the ATP-initiated superprecipitation of

Most of the spectra for the planet-host stars analyzed in this paper were studied in Papers I (Santos et al., 2000A&A...363..228S), II (Santos et al., 2001A&A...373.1019S), and III (Santos et al., 2003, Cat. . We refer the reader to these for a description of the data. During the last year, however, we have obtained spectra for 18 more planet host

With the 1 m Schmidt telescope of the Llano del Hato Observatory and the QUEST CCD camera, 380 deg2 of the sky have been surveyed for RR Lyrae variables in a band 2.3d wide in declination (centered at δ=-1°) and covering right ascensions from 4h1 to 6h1 and from 8h0 to 17h0. The bright limit (due to CCD saturation) and the faint limit are V~13.5

We discuss an ongoing study of the connection between galaxy merging/interaction and AGN activity, based on integral field spectroscopy. We focus on the search for AGN ionization in the central regions of mergers, previously not classified as AGNs. We present here the science case, the current status of the project, and plans for future