RESUMEN
Slow slip events (SSEs) accommodate a significant proportion of tectonic plate motion at subduction zones, yet little is known about the faults that actually host them. The shallow depth (<2 km) of well-documented SSEs at the Hikurangi subduction zone offshore New Zealand offers a unique opportunity to link geophysical imaging of the subduction zone with direct access to incoming material that represents the megathrust fault rocks hosting slow slip. Two recent International Ocean Discovery Program Expeditions sampled this incoming material before it is entrained immediately down-dip along the shallow plate interface. Drilling results, tied to regional seismic reflection images, reveal heterogeneous lithologies with highly variable physical properties entering the SSE source region. These observations suggest that SSEs and associated slow earthquake phenomena are promoted by lithological, mechanical, and frictional heterogeneity within the fault zone, enhanced by geometric complexity associated with subduction of rough crust.
RESUMEN
OBJECTIVE: To assess cognitive levels in an elderly Sicilian population and to evaluate the role of education and other sociodemographic characteristics in cognitive performance. BACKGROUND: The pattern of cognitive performance in the elderly has not been investigated extensively in well-defined Italian populations. This study was conducted as part of a door-to-door survey of common neurologic disorders (the Sicilian Neuro-Epidemiologic Study project). METHODS: Thirteen physicians administered an Italian version of the Short Portable Mental Status Questionnaire (SPMSQ) to all subjects aged 50 years or older who, on November 1, 1987, resided in either of two Sicilian municipalities (Terrasini, Palermo province, and Riposto, Catania province; n = 3,999). Performance was scored as the number of errors on the SMPSQ. To define cognitive impairment we corrected the score for education as suggested by Pfeiffer [J Am Geriatr Soc 1975;23:433-441]. RESULTS: The median SPMSQ score was equal to 2, and cognitive impairment was present in 4.6% of the subjects. In a bivariate analysis, age, sex, education, employment status at interview and principal lifetime occupation were all significantly associated with cognitive impairment. In a multivariate analysis, the same pattern was seen, except that principal lifetime occupation lost its significance. CONCLUSION: Our findings suggest that age, sex, education and employment status are the sociodemographic characteristics associated with cognitive impairment in the elderly as measured by the SPMSQ.