The scientific project of the small satellite of china

The efforts involved in developing a small satellite for scientific purposes in China in recent years are introduced in the present paper. The project is arranged on a case to case principle depending upon requirements and financial support. The space technology of a satellite and rockets, which have been developed over a relatively longer period in China, have been transferred to the scientific research of small satellites for improvement of the quality requirements. The surplus payloads of the rocket and satellite are used as the payloads of the small satellite and scientific experiments at a low cost. As an example, the project of balloon satellites for atmospheric research was successfully completed in 1991. The experience of the project management is of great benefit for further organization and arrangement of other projects. Opportunities exist for surplus payloads to be used in the future, and a small satellite for magnetospheric research will be launched in 1993.

Global distribution of Y-chromosome haplogroup C reveals the prehistoric migration routes of African exodus and early settlement in East Asia

The regional distribution of an ancient Y-chromosome haplogroup C-M130 (Hg C) in Asia provides an ideal tool of dissecting prehistoric migration events. We identified 465 Hg C individuals out of 4284 males from 140 East and Southeast Asian populations. We genotyped these Hg C individuals using 12 Y-chromosome biallelic markers and 8 commonly used Y-short tandem repeats (Y-STRs), and performed phylogeographic analysis in combination with the published data. The results show that most of the Hg C subhaplogroups have distinct geographical distribution and have undergone long-time isolation, although Hg C individuals are distributed widely across Eurasia. Furthermore, a general south-to-north and east-to-west cline of Y-STR diversity is observed with the highest diversity in Southeast Asia. The phylogeographic distribution pattern of Hg C supports a single coastal 'Out-of-Africa' route by way of the Indian subcontinent, which eventually led to the early settlement of modern humans in mainland Southeast Asia. The northward expansion of Hg C in East Asia started similar to 40 thousand of years ago (KYA) along the coastline of mainland China and reached Siberia similar to 15 KYA and finally made its way to the Americas. Journal of Human Genetics (2010) 55, 428-435; doi:10.1038/jhg.2010.40; published online 7 May 2010

Anomalous shift of the beating nodes in illumination-controlled In1-xGaxAs/In1-yAlyAs two-dimensional electron gases with strong spin-orbit interaction

The beating patterns in the Shubnikov-de Haas oscillatory magnetoresistance originating from zero-field spin splitting of two-dimensional electron gases (2DEGs) in In0.52Al0.48As/InxGa1-xAs/In0.52Al0.48As quantum wells with silicon delta doped on the upper barrier layer have been investigated by means of magnetotransport measurements before and after illumination. Contrary to the expectation, after each illumination, the beating nodes induced by the zero-field spin-splitting effect shift to lower and lower magnetic field due to the decrease in the zero-field spin-splitting energy of the 2DEGs. The anomalous phenomenon of the shift of the beating nodes and the decrease in spin-orbit coupling constants after illumination cannot be explained by utilizing the previous linear Rashba model. It is suggested that the decrease in the zero-field spin-splitting energy and the spin-orbit coupling constant arise from the nonlinear Rashba spin splitting.

In vitro construction of a recombinant human embryonic brain-derived neurotrophin-4 gene and pEGFP-N1 vector

BACKGROUND: Neurotrophin-4 (NT-4) can promote neuronal growth, development, differentiation, maturation, and survival. NT-4 can also improve recovery and regeneration of injured neurons, but cannot pass through the blood-brain barrier, which limits its ac

Strong Spin-Orbit Interactions in an InAlAs/InGaAs/InAlAs Two-Dimensional Electron Gas by Weak Antilocalization Analysis

Spin-orbit interactions in a two-dimensional electron gas were studied in an InAlAs/InGaAs/InAlAs quantum well. Since weak anti localization effects take place far beyond the diffusive regime, (i.e., the ratio of the characteristic magnetic field, at which the magnetoresistance correction maximum occurs, to the transport magnetic field is more than ten) the experimental data are examined by the Golub theory, which is applicable to both diffusive regime and ballistic regime. Satisfactory fitting lines to the experimental data have been achieved using the Golub theory. In the strong spin-orbit interaction two-dimensional electron gas system, the large spin splitting energy of 6.08 meV is observed mainly due to the high electron concentration in the quantum well. The temperature dependence of the phase-breaking rate is qualitatively in agreement with the theoretical predictions. (C) 2009 The Japan Society of Applied Physics

Optical properties of Mn+ doped GaAs

The above work was supported by the national Basic Research Program of China (2006cb604904, 2006cb604908), the hi-tech R & D program of China (2006aa03z0408, 2006aa03z0404), the scientific research Fund of Central South University of Forstry and Technology.

Nonlinear elastic waves in a monatomic chain with nonlinear interaction

Nonlinear wave equation for a one-dimensional anharmonic crystal lattice in terms of its microscopic parameters is obtained by means of a continuum approximation. Using a small time scale transformation, the nonlinear wave equation is reduced to a combined KdV equation and its single soliton solution yields the supersonic kink form of nonlinear elastic waves for the system.

Fabry-Perot microcavity modes observed in the micro-photoluminescence spectra of the single nanowire with InGaAs/GaAs heterostructure

We report on the fabrication of the nanowires with InGaAs/GaAs heterostructures on the GaAs(111) B substrate using selective-area metal organic vapor phase epitaxy. Fabry-Perot microcavity modes were observed in the nanowires with perfect end facets dispersed onto the silicon substrate and not observed in the free-standing nanowires. We find that the calculated group refractive indices only considering the material dispersion do not agree with the experimentally determined values although this method was used by some researchers. The calculated group refractive indices considering both the material dispersion and the waveguide dispersion agree with the experimentally determined values well. We also find that Fabry-Perot microcavity modes are not observable in the nanowires with the width less than about 180 nm, which is mainly caused by their poor reflectivity at the end facets due to their weak confinement to the optical field. (C) 2009 Optical Society of America