Climate as the dominant control on C<Subscript>3</Subscript> and C<Subscript>4</Subscript> plant abundance in the Loess Plateau: Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

Two modes of photosynthesis predominate in terres-REPORTS trial plants: the C3 and C4 modes[1]. The C3 mode is used by all of trees, bushes, and cold season grasses. The C4 mode is used by the most of tropical and warm season grasses. They are disadvantaged relative to C3 plants at high CO2/O2 ratios because of the additional energy ex-pense needed to concentrate CO2 in the bundle-sheath cells. At low CO2/O2, however, C4 plants can achieve a relatively high quantum yield by suppressin…     

New evidence for human occupation of the northern Tibetan Plateau, China during the Late Pleistocene

The described stone artifacts are recovered from the 70 m-high terrace (4600 m a.s.l.) at the southeastern shore of the Siling Co on the northern Tibetan Plateau. The terrace was formed during the Interstadial period before the LGM, ca. 40-30 ka B.P. based on paleoenvironmental research. The Paleoliths from the Siling Co provide evidence for early human occupation of the northern Tibetan Plateau. They show technological and typological affinities with the European Middle Paleolithic suggesting that the early human occupation here might relate to migratory waves during the Late Pleistocene that dispersed humans across the Old World.     

Preliminary study on LGM climate simulation and the diagnosis for East Asia

LGM climate study is a hot topic in international fields on global changes. Climate simulation in this study applies both common designs of 21 kaBP boundary conditions from the Paleoclimate Modeling Intercomparison Project (PMIP), including insolation, glaciation, sea surface temperature and atmospheric CO₂ concentration, and land surface conditions from Eurasia continent by compilation of geological evidence. The simulation outputs are in agreement with climate spatial patterns reconstructed by observation records. Sensitive experiment on land surface conditions shows that changes in vegetation would make significant impacts on temperature and precipitation. Particularly in the Tibetan Plateau, this change would increase in differences of winter and summer temperature, precipitation and P-E.     

Lake records and LGM climate in China

Chinese lake status database has provided systematic geological records of much higher lake level and fresher water than today at the LGM from western China. This wet condition was significant contrast with very dry conditions in eastern China. Together with lake studies from Eurasian continents, there was a wet-condition belt from the Mediterranean and the Middle East, Central Asia to western China. Palaeoclimate simulations confirmed that the wet conditions in western China were produced by decrease of the evaporation and increase of precipitation by positive anomaly of annual P-E of 70-95 mm/a between the LGM and today. The westerlies enhanced in the strength and shifted southwards-eastwards in the position, and the low thermal conditions in the Eurasian continent creating temperature 4-16℃ lower than today and relatively low evaporation, were the major two important climate conditions to yield cold-wet climates in western China.     

聚苯乙烯轻质混合土强度变形特性的微观试验研究

聚苯乙烯(EPS)轻质混合土是一种新型的轻质土工材料.通过扫描电镜对聚苯乙烯颗粒轻质混合土的微观性状进行了研究,从轻质混合土的微结构基本单元的形状、基本单元体的接触状态、基本单元体间的联结形式等微观角度解释了轻质混合土的强度变形机理.其微观结构研究表明,轻质混合土试样内部由于水泥水化、水解形成的网络状胶结结构是其强度的主要来源;轻质混合土中的EPS颗粒是通过置换效应和空间效应影响强度变形特性的.