Study on the movement and fracture of ＂isolated island＂ working face overburden by numerical simulation

For circumstances of medium-embedding depth and medium-hard surroundings in Jining No.2 Colliery, Yanzhou Group, by using software RFPA2D to simulate the process of overburden fracture, studied the overburden separation which was caused by working face exploitation, its fracture characteristics and the isolated island coalface（IIC） formation systematically in comparison method. After the recovery of the IIC, the surrounding separation areas which lied above the working face and bilateral goaved respectively form a connected region, a region that is like a saddle with low middle （35 times） and high sides. The top boundary line of the separation area is an arc. Then the fracture rise rapidly to 28 times of working thickness; while it is smaller （only 8-17 times recovery height） when extracting bilaterally, though the fracture plane both are in shape of an unsymmetrical trapezium. As the recovery of IIC makes side recoveries change from insufficiency to sufficiency, the consequentially rapid change of characteristics of overburden separation and fracture would enhance the representation degree of mining pressure of IIC.

Lineages differentiation and population structure of the light-vented bulbul Pycnonotus sinensis in China based on mitochondrial DNA and microsatellite analysis

The light-vented bulbul Pycnonotus sinensis is a small resident passerine that is found widely in central and south China,North Vietnam,and some East Asian islands,including Hainan,Taiwan and the Ryukyu Islands.Its subspecies status has been under considerable debate.A total of 10 subspecies have been proposed,but only 4 are widely recognized,including 1 continental taxon,P.s.sinensis,and 3 insular subspecies:P.s.hainanus,P.s.formosae and P.s.orii.Two mitochondrial DNA genes and 9 microsatellite loci were used to investigate the genetic divergence of this species,to identify the evolutionary status of 2 insular subspecies(P.s.hainanus and P.s.formosae)and to uncover probable historical causes that shaped them.The results reveal that P.s.formosae has diverged significantly from the other 2 subspecies because of a substantial time of isolation for populations on Taiwan Island.There was no significant genetic differentiation between P.s.sinensis and P.s.hainanus.The notable morphological difference in P.s.hainanus might be attributed to a rapid,recent adaptation to the tropical environment of Hainan Island.The low genetic divergence between P.s.sinensis and P.s.hainanus might result from a recent divergence or gene flow between them.Two insular subspecies of light-vented bulbul populations might have diverged recently from their continental relatives through a complex evolution history owing to island isolation,ecological isolation,and possibly even hybridization.Both P.s.hainanus and P.s.formosae should be considered important conservation units because of their morphological and genetic distinctiveness.