ABSTRACT
Speleothems can provide high-quality continuous records of the direction and relative paleointensity of the geomagnetic field, combining high precision dating (with U-Th method) and rapid lock-in of their detrital magnetic particles during calcite precipitation. Paleomagnetic results for a mid-to-late Holocene stalagmite from Dona Benedita Cave in central Brazil encompass ~1900 years (3410 BP to 5310 BP, constrained by 12 U-Th ages) of paleomagnetic record from 58 samples (resolution of ~33 years). This dataset reveals angular variations of less than 0.06° yr-1 and a relatively steady paleointensity record (after calibration with geomagnetic field model) contrasting with the fast variations observed in younger speleothems from the same region under influence of the South Atlantic Anomaly. These results point to a quiescent period of the geomagnetic field during the mid-to-late Holocene in the area now comprised by the South Atlantic Anomaly, suggesting an intermittent or an absent behavior at the multi-millennial timescale.
ABSTRACT
Using a Rational Emotive Behavior Therapy framework, the O'Kelly Women Beliefs Scale (O'Kelly, in press) was originally constructed in Australia to measure sex-role beliefs women may develop through sex-role stereotyping. Factor analysis of the 92 original items showed that 64 items loaded into a single component that accounted for 18.2% of the variance in a sample of 974 Australian women. The present exploratory study examined the psychometric properties of the OWBS in a sample of 202 women born and living in the US. A varimax rotation with cutoff eigenvalues of 3, showed that 37 items loaded into 3 components which accounted for 58.48% of the variance. The items were subsequently grouped into two factors: Irrationality, with a total of 27 items was created by merging component 1 and 3 (Pearson's r = 0.8 between them), and Rationality, with the 10 items from component 2. Analyses indicated a Cronbach's alpha of 0.91 for Factor 1, and a Cronbach's alpha 0.74 for Factor 2. Results indicate that this version of the instrument may be used to evaluate both the rational and irrational content of sex-role beliefs of women born in the US.
En el contexto de la Terapia Racional Emotivo-Conductual, se desarrolló la O'Kelly Women Beliefs Scale (OWBS) construída originalmente en Australia, para evaluar las creencias sobre el rol sexual que las mujeres pueden desarrollar como estereotipo. En una muestra de 974 mujeres australianas, el análisis factorial de los 92 reactivos originales mostró que 64 de ellos cargaron en un solo componente que explica el 18.2 % de la varianza total. El objetivo del presente estudio exploratorio es determinar la estructura factorial del OWBS, en 202 mujeres nacidas en E.E. U.U. La rotación Varimax con punto de corte de autovalor en 3, arrojó que 37 ítems cargan en tres componentes que explican el 58.48 % de la varianza total. Los reactivos se agruparon en dos factores: Irracionalidad, con un total de 27 reactivos que se integraron en los componentes 1 y 3 (r = 0.8) y Racionalidad, con 10 reactivos integrados en el componente 2. El alfa de Cronbach fue de 0.91 para el Factor 1 y de 0.74 para el Factor 2. Los resultados indican que esta versión del instrumento puede ser usada para evaluar tanto el contenido racional como el irracional de las creencias sobre el rol sexual de las mujeres nacidas en E.E. U.U.
ABSTRACT
A report of human footprints preserved in 40,000-year-old volcanic ash near Puebla, Mexico (http://www.royalsoc.ac.uk/exhibit.asp?id=3616&tip=1), was the subject of a press conference that stirred international media attention. If the claims (http://www.mexicanfootprints.co.uk) of Gonzalez et al. are valid, prevailing theories about the timing of human migration into the Americas would need significant revision. Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30+/-0.03 million years old. We conclude that either hominid migration into the Americas occurred very much earlier than previously believed, or that the features in question were not made by humans on recently erupted ash.