The Holocene is considered a period of relative climatic stability, but significant proxy data-model discrepancies exist that preclude consensus regarding the postglacial global temperature trajectory. In particular, a mid-Holocene Climatic Optimum,~9,000 to~5,000 years BP, is evident in Northern Hemisphere marine sediment records, but its absence from model simulations raises key questions about the ability of the models to accurately simulate climate and seasonal biases that may be present in the proxy records. Here we present new mid-Holocene sea surface temperature (SST) data from the western tropical Atlantic, where twentieth-century temperature variability and amplitude of warming track the twentieth-century global ocean. Using a new coral thermometer Sr-U, we first developed a temporal Sr-U SST calibration from three modern Atlantic corals and validated the calibration against Sr-U time series from a fourth modern coral. Two fossil corals from the Enriquillo Valley, Dominican Republic, were screened for diagenesis, U-series dated to 5,199 ± 26 and 6,427 ± 81 years BP, respectively, and analyzed for Sr/Ca and U/Ca, generating two annually resolved Sr-U SST records, 27 and 17 years long, respectively. Average SSTs from both corals were significantly cooler than in early instrumental and late instrumental periods at this site, by~0.5 and~0.75°C, respectively, a result inconsistent with the extended mid-Holocene warm period inferred from sediment records. A more complete sampling of Atlantic Holocene corals can resolve this issue with confidence and address questions related to multidecadal and longer-term variability in Holocene Atlantic climate.

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This paper reports on the impact that demographic characteristics have in the development of spatial visualization skills on two different offerings of CAD-related courses at two different institutions. The ultimate objective of this information is to identify factors that might be influencing visualization skills development. The importance placed on visualization skills improvement is due to the fact that they have been related to expected performance by students in the technical fields. The data for this study has been collected for a span of one year at two different institutions, with one institution offering a hybrid course including 2D and 3D topics, and the other institution offering a course with only 3D topics. The collected data includes several parameters, and in this study the focus will be on gender, race, previous CAD experience, and age. The measurement of the visualization skills is based on on the administration of the PSVT:R test at three different times during the semester: at the start, in the middle, and at the end. Previous comparative studies have resulted in no statistically significant differences between the two course offerings. Results from this study indicate that CAD experience and age play a more direct role in positively affecting the visualization skills of students.