The Late Quaternary Rio Grande Delta—A Distinctive, Underappreciated Geologic System

The delta of the Rio Grande/Rio Bravo in southernmost Texas and northern Tamaulipas is one of the major deltas of North America. Over 600,000 people live on the Holocene delta and river plain, and a million more on its Pleistocene ancestors, yet geo-logic knowledge is limited. Combining available geologic information with global satellite photography gives a balanced view of an important delta. The Holocene delta begins at a point west of San Benito, Texas, forming a classic eastward-opening delta. Over half of the delta lies south of the present Rio Grande drainage. The delta passes westward into a floodplain that becomes entrenched into older rocks westward to Roma. In this delta, distributary channels or resacas are extremely sinuous and show a pronounced levee rise. A yazoo stream in the floodplain cuts northward across Pleistocene deposits to form a displaced delta. The delta plain is extensively modified by eolian processes. Erosion of clay-rich algal mats from exposed esteros (large, shallow ephemeral lakes) create complex ‘clay dune’ deposits that form 6 m (20 ft) high hills (lomitas) on the flat plain. Dominant SE to SSE winds affect sand movement along the transgressive shorelines. Longshore movement is particularly effective on the north side of the delta, less so on the south side. The delta appears to have formed between 8000 and 3000 years BP by a robust, sediment-loaded Rio Grande. This period occurs during the Holocene Climatic Optimum, which was a dry time (altithermal) on the High Plains. Since 3000 years BP, the delta has been much less active and has been transgressed by barrier systems. The delta today is inactive, because of upstream reservoirs built since the 1940s. Before then, the river had irregular high discharge due to tropical systems and contributions from the upper Rio Grande system. The Pleistocene deltas that form the Beaumont surface underlying McAllen, Edinburg, and Harlingen probably exhibit similar landforms

Love is . . . an abstract word: the influence of phonological and semantic factors on verbal short-term memory in Williams syndrome

It has been claimed that verbal short-term memory in Williams syndrome is characterised by an over-use of phonological coding alongside a reduced contribution of lexical semantics. We critically examine this hypothesis and present results from a memory span task comparing performance on concrete and abstract words, together with a replication of a span task using phonologically similar and phonologically dissimilar words. Fourteen participants with Williams syndrome were individually matched to two groups of typically developing children. The first control group was matched on digit span and the second on vocabulary level. Significant effects were found for both the semantic and the phonological variables in the WS group as well as in the control groups, with no interaction between experimental variable and group in either experiment. The results demonstrate that, despite claims to the contrary, children and adults with WS are able to access and make use of lexical semantics in a verbal short-term memory task in a manner comparable to typically developing individuals

An Epidemiology of Information: Data Mining the 1918 Influenza Pandemic

An Epidemiology of Information: Data Mining the 1918 Influenza Pandemic seeks to harness the power of data mining techniques with the interpretive analytics of the humanities and social sciences to understand how newspapers shaped public opinion and represented authoritative knowledge during this deadly pandemic. This project makes use of the more than 100 newspaper titles for 1918 available from Chronicling America at the United States Library of Congress and the Peel’s Prairie Provinces collection at the University of Alberta Library. The application of algorithmic techniques enables the domain expert to systematically explore a broad repository of data and identify qualitative features of the pandemic in the small scale as well as the genealogy of information flow in the large scale. This research can provide methods for understanding the spread of information and the flow of disease in other societies facing the threat of pandemics