RESUMEN

Depending on intrinsic (e.g., radius ratio rule rLn/ rZr) and extrinsic factors (e.g., processing conditions), pyrochlore-type Ln2Zr2O7 oxides achieve variable degrees of structural disorder. We report on a systematic study of the structural and microstructural characteristics of the Gd2- xLn xZr2O7 system, exploring the effect of replacing Gd with a wide range of homovalent lanthanide ions (Ln = Nd, Sm, Dy, Ho, Y, and Er; x = 0.20 and 0.80). All compositions were prepared via a mechanochemical reaction between the corresponding oxides and characterized by X-ray diffraction (standard and synchrotron sources) using the Rietveld method, as well as by Raman spectroscopy. Irrespective of chemical composition, this study reveals that all compositions exhibit a fluorite-like structure. Furthermore, by firing each sample at 800 and 1400 °C, we are able to analyze the transition to pyrochlore-like structures, featuring different degrees of disorder, in all but Gd1.20Y0.80Zr2O7, which retains the fluorite structure even after heating. The structural data are used to assess the existing criteria for predicting the formation and stability of the pyrochlore structure; according to this analysis, the simple radius ratio rule ( rLn/ rZr), provides a useful and sufficiently robust criterion. Because the pyrochlore structure has a strong tendency to disorder, it is not possible to define an empirical index similar to the Goldschmidt tolerance factor for perovskite.

RESUMEN

OBJECTIVE: In Mexico, cervical uterine cancer (CUC) is one of the leading causes of death among women, however a low degree of participation in the early detection programs has been found. This study is aimed at describing the social determinants of knowledge related to cervical uterine cancer and proper testing being conducted by establishing the social differences with regard thereto among a population of female employees at a public university in Mexico. METHODS: An analytical cross-sectional study was made. During the March-April 2003 period, a survey was conducted of a representative sample of the female employees who were working at a public university (n=228), 110 of whom were professors (PF) and 118 administrative staff (AS). This population was chosen due to the major socioeconomic differentiation thereof in terms of their job positions (PF versus AS), thus affording the possibility of evaluating the bearing social inequality has on health-related behavior. The survey explored three aspects: living conditions, knowledge of CUC and of proper cervical uterine cancer detection testing. RESULTS: The female professors showed higher levels of income,schooling and knowledge of CUC and of cervical uterine cancer detection testing than the administrative staff. Income and schooling were positively related to the knowledge regarding cervical uterine cancer, cervical uterine cancer detection testing being related to the latter. CONCLUSIONS: Socioeconomic inequality among the women studied was reflected in differences in the degree of knowledge and in cervical uterine cancer detection testing being undergone. These differences are associated, above all, to the differences in the level of schooling.

OBJETIVO: En México el cáncer cérvicouterino (CACU) es una de las principales causas de muerte en mujeres; sin embargo, se ha encontrado una baja participación en los programas de su detección oportuna (DOCACU). El objetivo de este estudio fue describir los determinantes sociales del conocimiento sobre el cáncer cérvicouterino y la realización de la detección oportuna estableciendo las diferencias sociales que al respecto muestra una población de mujeres trabajadoras de una universidad pública de México. METODOS: Se realizó un estudio transversal analítico. Entre marzo y abril de 2003 se aplicó una encuesta a una muestra representativa de las trabajadoras que laboraban en una universidad pública (n=228), 110 eran académicas (AC) y 118 administrativas (AD). Se eligió esta población por su elevada diferenciación socioeconómica en función del puesto laboral (AC vs. AD), esto permitió evaluar la influencia de la desigualdad social sobre las conductas en salud. La encuesta exploró tres aspectos: condiciones de vida, conocimiento del CACU y DOCACU. RESULTADOS: Las mujeres académicas mostraron mayores niveles de ingreso, escolaridad, conocimiento del CACU y DOCACU que las administrativas. El ingreso y la escolaridad se relacionaron positivamente con el conocimiento sobre el cáncer cervicouterino, la realización de detección oportuna se relacionó con este último. CONCLUSIONES: La desigualdad socioeconómica entre las mujeres estudiadas se reflejó en diferencias en el grado de conocimiento y en la práctica de la detección oportuna. Estas diferencias se asocian,sobre todo, a las diferencias en el grado de escolaridad.