云南18 个民族Y染色体双等位基因单倍型频率的主成分分析

世居云南的少数民族中,壮、傣、水、布依、布朗、德昂、佤、彝、白、怒、哈尼、傈僳、拉祜、纳西、景颇、阿昌、基 诺和独龙18 个民族是由“羌”、“濮”、“越”3 大部落群体演化而来,是云南的土著居民。利用PCR2RFL P 方法对这18 个土著民族进行Y染色体上13 个双等位基因位点进行基因分型。结果显示,不同历史族源的民族群体在Y染 色体双等位基因单倍型分布上具有一定的差异:在百越后裔民族群体中以单倍型H11 、H12 为主要分布;在氐羌后 裔民族中以单倍型H5 、H6 和H8 为主要分布;在百濮后裔民族群体中主要单倍型分布为H6 、H8 和H11 。进一步 主成分分析表明,百越后裔民族群体和氐羌后裔民族在主成分图上聚为两组,提示父系基因库有不同的来源,与历 史记载相印证。

Photonic switch and NOT logic gate based on the hybrid integration of a GaAsVCSEL and a GaAs MISS

The hybrid integrated photonic switch and not logic gate based on the integration of a GaAs VCSEL (Vertical Cavity Surface Emitting Lasers) and a MISS (Metal-Insulator-Semiconductor Switches) device are reported. The GaAs VCSEL is fabricated by selective etching and selective oxidation. The Ultra-Thin semi-Insulating layer (UTI) of the GaAs MISS is formed by using oxidation of A1As that is grown by MBE. The accurate control of UTI and the processing compatibility between VCSEL and MISS are solved by this procedure. Ifa VCSEL is connected in series with a MISS, the integrated device can be used as a photonic switch, or a light amplifier. A low switching power (10 mu W) and a good on-off ratio (17 dB contrast) have been achieved. If they are connected in parallel, they perform a photonic NOT gate operation.

Design and fabrication of GaAs OMIST photodetector

We designed and fabricated GaAs OMIST (Optical-controlled Metal-Insulator-Semiconductor Thyristor) device. Using oxidation of A1As layer that is grown by MBE form the Ultra-Thin semi-Insulating layer (UTI) of the GAAS OMIST. The accurate control and formation of high quality semi-insulating layer (AlxOy) are the key processes for fabricating GaAs OMIST. The device exhibits a current-controlled negative resistance region in its I-V characteristics. When illuminated, the major effect of optical excitation is the reduction of the switching voltage. If the GaAs OMIST device is biased at a voltage below its dark switching voltage V-s, sufficient incident light can switch OMIST from high impedance low current"off"state to low impedance high current "on"state. The absorbing material of OMIST is GaAs, so if the wavelength of incident light within 600 similar to 850nm can be detected effectively. It is suitable to be used as photodetector for digital optical data process. The other attractive features of GaAs OMIST device include suitable conducted current, switching voltage and power levels for OEIC, high switch speed and high sensitivity to light or current injection.