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Here, we describe the characterization of a radioligand selective for GluN2B‐containing NMDA receptors, 3‐[3H] 1‐(azetidin‐1‐yl)‐2‐(6‐(4‐fluoro‐3‐methyl‐phenyl)pyrrolo[3,2‐b]pyridin‐1‐yl)ethanone ([3H]‐JNJ‐ GluN2B‐5). In rat cortical membranes, the compound bound to a single site, and the following kinetic parameters were measured; association rate constant Kon = 0.0066 ± 0.0006 min−1 nM−1, dissociation rate constant Koff = 0.0210 ± 0.0001 min−1 indicating calculated KD = Koff/Kon = 3.3 ± 0.4 nM, (mean ± SEM, n = 3). The equilibrium dissociation constant determined from saturation binding experiments in rat cortex was KD of 2.6 ± 0.3 nM (mean ± SEM, n = 3). In contrast to the widely used GluN2B radioligand [3H]‐Ro 25‐6981, whose affinity Ki for sigma 1 and sigma 2 receptors are 2 and 189 nM, respectively, [3H]‐JNJ‐GluN2B‐5 exhibits no measurable affinity for sigma 1 and sigma 2 receptors (Ki > 10 μM for both) providing distinct selectivity advantages. Anatomical distribution of [3H]‐JNJ‐GluN2B‐5 binding sites in rat, mouse, dog, monkey, and human brain tissue was studied using in vitro autoradiography, which showed high specific binding in the hippocampus and cortex and negligible binding in the cerebellum. Enhanced selectivity for GluN2B‐containing receptors translated to a good signal‐to‐noise ratio in both in vitro radioligand binding and in vitro autoradiography assays. In conclusion, [3H]‐JNJ‐GluN2B‐5 is a high‐affinity GluN2B radioligand with excellent signal‐to‐noise ratio and unprecedented selectivity. [ABSTRACT FROM AUTHOR]

The relationship between Andean uplift and extreme desiccation of the west coast of South America is important for understanding the interplay between climate and tectonics in the Central Andes, yet it is poorly understood. Here we use soil morphological characteristics, salt chemistry, and mass independent fractionation anomalies ([[DELTA].sup.17]O values) in dated paleosols to reconstruct a middle Miocene climatic transition from semiaridity to extreme hyperaridity in the Atacama Desert. Paleosols along the southeastern margin of the Calama Basin change from calcic Vertisols with root traces, slickensides, and gleyed horizons to an extremely mature salic Gypsisol with pedogenic nitrate. We interpret this transition, which occurred between 19 and 13 Ma, to represent a change in precipitation from >200 mm/yr to 2 km; the uplift blocked moisture from the South American summer monsoon from entering the Atacama. The mid-Miocene Gypsisol with pedogenic nitrate is located at elevations between 2900 and 3400 m in the Calama Basin, significantly higher than modern nitrate soils, which occur below ~2500 m. Modern and Quaternary soils in this elevation zone contain soil carbonate and lack pedogenic gypsum and nitrate. We infer that >900 m of local surface uplift over the past 10 m.y. displaced these nitrate paleosols relative to modern nitrate soils and caused a return to wetter conditions in the Calama Basin by decreasing local air temperatures and creating an orographic barrier to Pacific air masses. Keywords: Atacama Desert, Andes, paleosols, Calama Basin, soil nitrate.

In the ancient Near East, floors, walls, roads, aqueducts and even art were constructed of mortar and plaster. Lime cements were used to make everything from figurines to cisterns and mikvahs (ritual baths), making them virtually ubiquitous at archaeological sites from the Neolithic period on. The beginnings of plaster technology appear to be linked with the establishment of large towns around the seventh millennium BCE. (1) The inhabitants of well-known Neolithic sites like Jericho, Tell Ramad, Gatal Hoyuk and 'Ain Ghazal used plaster in a variety of ways. Imagine, therefore, what it would mean for archaeology if we could accurately determine the age of the mortar and plaster used by these cultures? This is what many scientists who work with radiocarbon dating have been trying to do for the last thirty years, with varying levels of success. Recently, however, investigators have been successful at dating plaster from Siloam' s Tunnel in Jerusalem and Khirbet Qana in the Lower Galilee. Others are working to date many other structures from the Egyptian pyramids to Trojan's markets in Rome.

The authors demonstrate the potential for dating structures in Near Eastern archaeology by applying AMS radiocarbon to organic inclusions found in mortar and plaster. The method was successfully applied to date and sequence excavated walls and floors, and to spot-date structures exposed in surveys. Keywords: AMS [sup.14]C dating, plaster, mortar, Khirbet Qana, Israel, Introduction Although radiocarbon dating has been utilised to date important artefacts such as the Dead Sea Scrolls (Jull et al. 1995), archaeologists working on historic-period sites in the Near East [...]

In northern Chile, precipitation in the High Andes (>3500 m) recharges groundwater systems that flow down the Pacific slope and feed large aquifers in the hyperarid Atacama Desert. Wetlands, which are often found along the base of the Andes, mark locations where the water table intersects the land surface. At these locations, paleo--wetland deposits, which are present as terraces between 3 and 20 m above modern wetlands, record past water-table heights along the Andean front and are used to reconstruct changes in groundwater discharge. Paleo--wetland deposits in the central Atacama Desert (lat 22[degrees]-24[degrees]S) record an episode (>15.4-9 ka) of high water tables followed by an episode (8-3 ka) of moderately high water tables. Elevated water tables result from increased groundwater discharge and ultimately from enhanced recharge in the Andes. The concordance of results from three separate hydrologic systems suggests that changes in groundwater discharge and recharge are regional and reflect climatic fluctuations. This interpretation is supported by close agreement with other paleoclimatic records in the region. The periods of greater groundwater discharge were separated by episodes (9-8 and 3-0 ka) of significant groundwater lowering and stream incision, implying greatly diminished discharge. The central Atacama and Andes (lat 22[degrees]-24[degrees]S) receive precipitation mainly from moist air masses transported from the Amazon Basin by the South American Summer Monsoon (SASM). Increases in groundwater recharge are therefore thought to reflect an increase in the frequency and/or moisture content of SASM air masses crossing the Andes. Fluctuations in SASM precipitation have previously been linked to summer insolation in the Southern Hemisphere. The wettest period in the central Atacama (>15.4-9 ka), however, coincides with a minimum in austral-summer insolation at 10 ka, suggesting that regional summer insolation is not a dominant influence on the SASM. Instead, intensification of the SASM may be linked to extraregional forcings such as the Walker Circulation. Keywords: Atacama Desert, wetlands, springs, paleohydrology, South America.