Sun Nan

Oldest Directly Dated Remains of Sheep in China

The origins of domesticated sheep (Ovis sp.) in China remain unknown. Previous workers have speculated that sheep may have been present in China up to 7000 years ago, however many claims are based on associations with archaeological material rather than independent dates on sheep material. Here we present 7 radiocarbon dates on sheep bone from Inner Mongolia, Ningxia and Shaanxi provinces. DNA analysis on one of the bones confirms it is Ovis sp. The oldest ages are about 4700 to 4400 BCE and are thus the oldest objectively dated Ovis material in eastern Asia. The graphitisised bone collagen had δ13C values indicating some millet was represented in the diet. This probably indicates sheep were in a domestic setting where millet was grown. The younger samples had δ13C values indicating that even more millet was in the diet, and this was likely related to changes in foddering practices

Structural adaptive and optimal speckle filtering in multilook full polarimetric SAR images

Abstract A novel approach is proposed for speckle reduction in multilook full polarimetric SAR images. In contrast to others, this approach adopts an enhanced structure detection method to estimate the parameters of the polarimetric covariance matrix for the multilook polarimetric whitening filtering (MPWF) algorithm and thus a structural adaptive and optimal specklefflter is developed. To evaluate the present approach, NASA SIR-C/XSAR, L band, four-look processed polarimetric SAR data of the Tian-Mountain Forest is used for simulation. Experimental results demonstrate the effectiveness of this novel filtering algorithm in case of both speckle reduction and preservation of texture information. Comparisons with other methods are also made.

Records of element geochemistry on the bronze smelting in Hexi Corridor since 4200 aBP

The utilization and smelting of metal is a revolutionary event during developing process of human society.The records of element geochemistry from lacustrine sediment at Lake Tiaohu in Hexi Corridor,during Holocene indicated that the high values of element such as Cu,Pb,Zn,and Ni appeared in the period of 10500-9500 and 8000-7200cal aBP,responding to the episode of glacial meltwater rising in the period of increasing temperature in early Holocene of the and the period of precipitation strength during Holocene optimum,respectively.The highest peak values of Cu,As,Pb,Zn and Ni appeared between 4200 and 3700cal aBP.Additionally,the secondary high values of Cu,Pb,Zn and Ni appeared in the period of 3000-2700cal aBP and 2100- 1900cal aBP.The element abnormality between 4200 and 3700cal aBP record the earliest bronze smelting in Northwest China and the element of arsenic was the major component in bronze alloy in this period.The element high values of Cu,Pb,Zn,Ni in Western Zhou Dynasty(3000-2700cal aBP) and Han Dynasty(2100-1900cal aBP) were probably the result of bronze smelting by ancient people.The record of element geochemistry could identify the starting-end time of bronze smelting,and it also provided the message on the component characteristic of bronze alloy in different periods.