A Plant Needs Ants like a Dog Needs Fleas: Myrmelachista schumanni Ants Gall Many Tree Species to Create Housing

Hundreds of tropical plant species house ant colonies in specialized chambers called domatia. When, in 1873, Richard Spruce likened plant-ants to fleas and asserted that domatia are ant-created galls, he incited a debate that lasted almost a century. Alth

Altitudinal Ranging of Black-Crested Gibbons at Mt. Wuliang, Yunnan: Effects of Food Distribution, Temperature and Human Disturbance

We studied the altitudinal ranging of one habituated group of black-crested gibbons (Nomascus concolor) at Dazhaizi, Mt. Wuliang, Yunnan, China, between March 2005 and April 2006. The group ranged from 1,900 to 2,680 m above sea level. Food distribution was the driving force behind the altitudinal ranging patterns of the study group. They spent 83.2% of their time ranging between 2,100 and 2,400 m, where 75.8% of important food patches occurred. They avoided using the area above 2,500 m despite a lack of human disturbance there, apparently because there were few food resources. Temperature had a limited effect on seasonal altitudinal ranging but probably explained the diel altitudinal ranging of the group, which tended to use the lower zone in the cold morning and the higher zone in the warm afternoon. Grazing goats, the main disturbance, were limited to below 2,100 m, which was defined as the high-disturbance area (HDA). Gibbons spent less time in the HDA and, when ranging there, spent more time feeding and travelling and less time resting and singing. Human activities directly influenced gibbon behaviour, might cause forest degradation and create dispersal barriers between populations. Copyright (C) 2010 S. Karger AG, Basel

Influence of Potamogeton crispus growth on nutrients in the sediment and water of Lake Tangxunhu

An incubation experiment was performed on Potamogeton crispus (P. crispus) using sediment collected from Lake Tangxunhu in the center of China, in order to determine the effects of plant growth on Fe, Si, Cu, Zn, Mn, Mg, P, and Ca concentrations in the sediments and overlying waters. After 3 months of incubation, Ca, Mg, and Si concentrations in the water column were significantly lower, and P and Cu concentrations were significantly higher than in unplanted controls. The effect of P. crispus growth on sediment pore waters and water-extractable elements varied. Concentrations of Ca, Mg, Si, Fe, Cu, and Zn were significantly higher, and P was significantly lower, than in pore waters of the control. Water-extracted concentrations of Fe, Mg, and Si in the sediments were lower, and P was higher, than in the control. Presence of P. crispus generally enhanced concentration gradients of elements between pore waters and overlying waters but not for P. The growth of P. crispus was associated with an increase in water pH and formation of root plaques, resulting in complex effects on the sediment nutritional status.

Microphotoluminescence investigation of InAs quantum dot active region in 1.3 mu m vertical cavity surface emitting laser structure

Microphotoluminescence (mu-PL) investigation has been performed at room temperature on InAs quantum dot (QD) vertical cavity surface emitting laser (VCSEL) structure in order to characterize the QD epitaxial structure which was designed for 1.3 mu m wave band emission. Actual and precise QD emission spectra including distinct ground state (GS) and excited state (ES) transition peaks are obtained by an edge-excitation and edge-emission (EEEE) mu-PL configuration. Conventional photoluminescence methods for QD-VCSELs structure analysis are compared and discussed, which indicate the EEEE mu-PL is a useful tool to determine the optical features of the QD active region in an as-grown VCSEL structure. Some experimental results have been compared with simulation results obtained with the aid of the plane-wave admittance method. After adjustment of epitaxial growth according to EEEE mu-PL measurement results, QD-VCSEL structure wafer with QD GS transition wavelength of 1300 nm and lasing wavelength of 1301 nm was obtained.

地带性多年冻土区小流域水文状况对水热季节变化的响应

大兴安岭北部是我国唯一一片地带性连续多年冻土分布区，也是欧亚大陆地带性多年冻土分布区的南缘，因此对气候变化的响应十分敏感。全球变暖必然会影响到冻土土壤水分状态的变化，从而对冻土区的流域水文状况产生影响；小流域是区域研究的主要对象，冻土活动层变化的最直接后果就是引起流域内水文状况发生变化。本研究利用DEM数据划分小流域，在划分出的小流域的基础上，探讨了影响流域流量变化的几个因子，包括降水、蒸散(Evapotranspiration, ET)和土壤持水，初步简化了流域水量平衡方程，可为进一步研究提供基础。主要包括以下方面的内容： a)平均温度的升高必然会影响到冻土土壤水分状态的变化，从而导致区域小流域水文状况随之变化； b)融深与海拔高度存在一定的相关关系，融深随海拔的升高而增加；土壤水分随海拔变化的规律并不明显。年内降水主要集中在每年的5月份到10月份；11月份和12月份降水一般比春季的多，这两个月份气温很低，降水形式主要是雪。不同地点不同海拔下冻土活动层土壤水分含量变化很大，这和当地的环境条件有关，如地表覆被、土壤类型、坡度、坡向等。 c)参考植被蒸散呈明显的周期性波动规律。每年同期蒸散大致维持在同一水平上。从年初到年中，流域内蒸散呈不断增加的趋势。但是变化规律又稍有不同，每年大致从1月份到4月份，蒸散随时间变化很快，几乎呈线性增加。但是从4月中旬开始，到下半年的9月中旬，ET0呈震荡变化趋势。4月中旬开始，蒸散开始震荡增加，到7月份左右达到最大，然后开始震荡降低，大约到9月中旬或10月初开始转为近似线性减少趋势。 d)土壤水分含量的变化ΔW���以表示为下式：ΔW=R-(0.260Rn-0.036N) Kc+c；其中，ΔW���土壤水分含量的变化；R流域出口处流量；Rn为太阳净辐射；N为白昼长度；Kc植被系数；c为常数。 上述研究结果可以为进一步分析年内冻土湿地水分状况对温度变化的响应提供基础，也可为气候变化条件下冻土湿地水文过程的响应研究提供参考。

Last deglaciation in the Okinawa Trough: Subtropical northwest Pacific link to Northern Hemisphere and tropical climate

IEECAS SKLLQG

PPA在LLDPE/LDPE农膜加工中的应用

本工作以LLDPE／LDPE为基料，添加氟弹性体加工改性剂DynamarPPA，采用LDPE挤出机加工农膜。结果表明，挤出机加工LLDPE的能力大幅度地提高，使共混物中LLDPE含量从原来的40％增加到80％，薄膜的物理机械性质亦有明显改善，而主机电流和挤出量未见变化。在添加无滴剂母料条件下，可加工LLDPE总含量达95％的无滴膜，且该膜的力学性质和光学性质均住。

LLDPE/LDPE薄膜加工改性剂PPA

以LLDPE/LDPE共混树脂为基料,添加加工改性剂氟弹性体PPA,采用挤出吹塑成型加工薄膜制品。以LLDPE/LDPE质量比为1/2作空白样。按每克试样总量中含500μg PPA的比例添加PPA,当共混物中LLDPE含量为1/3时,挤出机电流下降,薄膜的透光率增加,雾度降低;LLDPE含量为60％时,挤出机电流未变而产量提高,薄膜的透光率和雾度变化不大;继续增加LLDPE比例时,挤出机电流和雾度增加。薄膜的拉伸性能随LLDPE比例增大显著提高,且纵横向的取向度变小。