Effects of the magnetic dipole moment of charged vector mesons in their radiative decay distribution

We consider the effects of anomalous magnetic dipole moments of vector mesons in the decay distribution of photons emitted in two-pseudoscalar decays of charged vector mesons. By choosing a kinematical configuration appropriate to isolate these effects from model-dependent and dominant bremsstrahlung contributions, we show that this method can provide a valid alternative for a measurement of the unknown magnetic dipole moments of charged vector mesons.Comment: Latex, 11 pages incl. 3 .ps figures, to appear in Phys. Rev.

Further remarks on isospin breaking in charmless semileptonic B decays

We consider the isospin breaking corrections to charmless semileptonic decays of B mesons. Both, the recently measured branching ratios of exclusive decays by the CLEO Collaboration and the end-point reion of the inclusive lepton spectrum in form factor models, can be affected by these corrections. Isospin corrections can affect the determination of |V_ub| from exclusive semileptonic B decays at a level comparable to present statistical uncertainties.Comment: Latex, 7 pages, 1 .ps figure, to appear in Phys. Rev.

Learning Languages On-Line: The Role of Interpersonal Relations. [abstract].

This paper reports on a pilot study examining how the communication patterns of second language learners may change in the course of one semester using a synchronous text-based Computer-Mediated Communication (CMC) environment. This paper examines the dynamics of interpersonal interactions and social processes of a cohort of forty-three university students, with at intermediate level of competence in Spanish. The students participated in five synchronous CMC discussions in small groups. The paper also considers how CMC can provide an additional context for the creation of a learning community by providing opportunities to engage in meaningful social interaction in a non-threatening and supportive environment

Cerrando la brecha entre nativos e inmigrantes digitales a través de las competencias informáticas e informacionales

En este texto hacemos una reflexión acerca de las diferencias entre los llamados "nativos" e "inmigrantes digitales", y aportamos datos que permitan identificar si un grupo tiene mayores ventajas sobre otro en relación con la enseñanza y el aprendizaje en esta era digital. Proponeos la adquisición y el desarrollo de competencias informáticas e informaciones en ambos grupos como estrategia para reducir la brecha digital "blanda" que priva en el sistema educativo e invitamos a resolver las interrogantes: ¿Los docentes estamos preparados para enseñar las nuevas asignaturas y las viejas materias, pero con nuevas formas?, y ¿los alumnos contamos con las tradicionales competencias informaciones requeridas para resolver nuevos problemas y tomar decisiones en escenarios futuros

Variation of the ultraviolet extinction law across the Taurus-Auriga star forming complex. A GALEX based study

The Taurus-Auriga molecular complex (TMC) is the main laboratory for the study of low mass star formation. The density and properties of interstellar dust are expected to vary across the TMC. These variations trace important processes such as dust nucleation or the magnetic field coupling with the cloud. In this article, we show how the combination of near ultraviolet (NUV) and infrared (IR) photometry can be used to derive the strength of the 2175 \AA\ bump and thus any enhancement in the abundance of small dust grains and PAHs in the dust grains size distribution. This technique is applied to the envelope of the TMC, mapped by the GALEX All Sky Survey (AIS). UV and IR photometric data have been retrieved from the GALEX-AIS and the 2MASS catalogues. NUV and K-band star counts have been used to identify the areas in the cloud envelope where the 2175 \AA\ bump is weaker than in the diffuse ISM namely, the low column density extensions of L1495, L1498 and L1524 in Taurus, L1545, L1548, L1519, L1513 in Auriga and L1482-83 in the California region. This finding agrees with previous results on dust evolution derived from Spitzer data and suggests that dust grains begin to decouple from the environmental galactic magnetic field already in the envelope.Comment: Accepted in Monthly Notices of the Royal Astronomical Societ

MOSAIX: a tool to built large mosaics from GALEX images

Large sky surveys are providing a huge amount of information for studies of the interstellar medium, the galactic structure or the cosmic web. Setting into a common frame information coming from different wavelengths, over large fields of view, is needed for this kind of research. GALEX is the only nearly all-sky survey at ultraviolet wavelengths and contains fundamental information for all types of studies. GALEX field of view is circular embedded in a squared matrix of 3840 x 3840 pixels. This fact makes it hard to get GALEX images properly overlapped with the existing astronomical tools such as Aladin or Montage. We developed our own software for this purpose. In this article, we describe this software and makes it available to the community.Comment: 7 pages, including 8 figures, accepted by Astrophysics and Space Scienc

Tobacco use in the third trimester of pregnancy and its relationship to birth weight. A prospective study in Spain

Background Few studies have been carried out in Spain examining the use of tobacco amongst expectant mothers and its effect on birth weight. Aims To observe the proportion of expectant mothers who smoke during their pregnancy, and the impact of tobacco consumption on maternal and birth weight. We also aimed to identify the trimester of pregnancy in which tobacco use produced the greatest reduction in birth weight. Methods Prospective observational study in Spain. A random sampling strategy was used to select health centres and participant women. A total of 137 individuals were enrolled in the study. Exposure to tobacco was measured through a self-reported questionnaire. Regressions were performed to obtain a predictive model for birth weight related to smoking. Findings Overall, 35% of study participants were smokers during the pre-gestational period (27% in the first trimester, 21.9% in the second and 21.2% in the third). 38.7% of smoking cessation attempts took place in the third-trimester. Pregnant women who smoked up to the third trimester had a higher risk of giving birth to a baby under 3000 g, compared to non-smokers (OR = 5.94, CI 95%: 1.94–18.16). Each additional unit of tobacco consumed daily in the 3rd trimester led to a 32 g reduction in birth weight. Conclusion An important proportion of pregnant women in Spain smoke during pregnancy. Pregnant women exposed to tobacco have newborns with lower birth weight. Smoking during the 3rd trimester of pregnancy is associated with the greatest risk of lower birth weight