Description: The hyper-arid Qaidam Basin is a major dust source area in China. Mineral materials that settled during 11 dust storms from November 2003 to April 2005 in the northern Qaidam Basin were comprised of an amount of fine particles. The particles 〈20 mu m varied between 11.4 and 19.4 vol.-%, while the mean volume percentages of 〈2, 2-5, 5-10 and 10-20 mu m particles were 2.9, 3.6, 4.0 and 5.3 vol.-%, respectively. The deposits were characterised by very similar multi-modal grain size distributions. Stronger winds (〉14 m s(-1) at a height of 10 m above ground) during these dust storms were unfavourable for the gravitational settling of single fine mineral grains. Fine particles might instead settle either by forming aggregates or by adhering to larger grains. As such, the great amount of clay and fine silt in Chinese loess deposits can largely be correlated with dust storm processes and are likely derived from proximal source areas. Fine dust records from the Chinese Loess Plateau (CLP) therefore have to be interpreted cautiously as climatic proxies for changes in the westerlies. (C) 2010 Elsevier Ltd. All rights reserved.

Description: Independent dust provenance data play an important role in understanding changes in the atmospheric dust loading over geological time. Major elemental compositions and grain-size characteristics of the aeolian deposits (Xiangshan (XS) section) at the southeastern margin of the Tengger Desert in northwestern China demonstrate that the deposits are an intermediate product of the transportation of aeolian materials from the dust source area (deserts) to the dust depositional regions (Chinese Loess Plateau) that were likely formed by dust storm processes. The 〉 40 μm and 63–178 μm fractions and the ratio of SiO2/TiO2 of the XS section were used as proxies to reconstruct the surface wind regime over the last 20 kyr. The results show that the surface winds were much stronger and fluctuate acutely from 19.1 to 11.4 kyr. The winds gradually attenuated after the beginning of the Holocene and reached a minimum between 4.0 and 3.5 kyr BP. A sharp increase in surface winds occurred after 2.5 kyr BP. The surface winds in the Asian dust source area are largely consistent with the changes in winter monsoon strength documented by the Chinese loess deposits. Also, the stronger surface winds from 19.1 to 11.4 kyr coincide with the high mineral dust concentration determined from the Greenland ice core, except for the period of Bölling–Allerød (B/A), when the atmospheric dust may have been washed out by enhanced global hydrological cycles although dust was still emitted from source areas. This suggests that the stronger surface winds in dust source areas can enhance the atmospheric dust loadings during the late glacial. The weakening surface wind regime during the Holocene may have greatly contributed to the decrease in dust concentration of the remote dust records. The paleo-environmental changes in the study area since 42.5 kyr BP are broadly in agreement with other adjacent records. However, the possible warm and humid spell of 42.5–19.1 kyr BP still requires verification.

Description: The dopaminergic and renin–angiotensin systems interact to regulate blood pressure. Disruption of the D 4 dopamine receptor gene in mice produces hypertension that is associated with increased renal angiotensin type 1 (AT 1 ) receptor expression. We hypothesize that the D 4 receptor can inhibit AT 1 receptor expression and function in renal proximal tubule cells from Wistar–Kyoto (WKY) rats, but the D 4 receptor regulation of AT 1 receptor is aberrant in renal proximal tubule cells from spontaneously hypertensive rats (SHRs). The D 4 receptor agonist, PD168077, decreased AT 1 receptor protein expression in a time- and concentration-dependent manner in WKY cells. By contrast, in SHR cells, PD168077 increased AT 1 receptor protein expression. The inhibitory effect of D 4 receptor on AT 1 receptor expression in WKY cells was blocked by a calcium channel blocker, nicardipine, or calcium-free medium, indicating that calcium is involved in the D 4 receptor–mediated signaling pathway. Angiotensin II increased Na + -K + ATPase activity in WKY cells. Pretreatment with PD168077 decreased the stimulatory effect of angiotensin II on Na + -K + ATPase activity in WKY cells. In SHR cells, the inhibitory effect of D 4 receptor on angiotensin II–mediated stimulation of Na + -K + ATPase activity was aberrant; pretreatment with PD168077 augmented the stimulatory effect of AT 1 receptor on Na + -K + ATPase activity in SHR cells. This was confirmed in vivo; pretreatment with PD128077 for 1 week augmented the antihypertensive and natriuretic effect of losartan in SHRs but not in WKY rats. We suggest that an aberrant interaction between D 4 and AT 1 receptors may play a role in the abnormal regulation of sodium excretion in hypertension.