科研成果

Dielectric waveguide with deep subwavelength mode confinement based on coupled semiconductor nanowires is proposed. Through the coupling between two adjacent nanowires with high refractive indexes, light can be efficiently confined in the nano-gap between the nanowires with a low refractive index. Numerical simulations indicate that the effective mode area of such a waveguide can be as small as lambda(2)(0)/200, which is one order of magnitude smaller than that of a single nanowire, and such a mode confinement is comparable to that of hybrid plasmonic waveguide. It is also shown that from the view of real applications, possible existing low refractive index oxidization layers of nanowires, low refractive index substrate and small deviation of nanowire dimensions do not have significant influence on the property of the waveguide. As the propagation length is theoretically infinite for dielectric waveguides, such a coupled nanowire waveguide with deep subwavelength mode confinement may have important applications in future integrated photonic circuits.

DNA混合分析技术的广泛使用,能够明显降低研究的工作量和成本,然而仍然有其自身局限,例如损失了大量个体遗传信息、测量误差较大等。为了尽量克服DNA混合分析技术的自身问题,其检测和分析方法在不断发展与完善。在单体型频率估计方面,基于最大期望(expectation-maximization,EM)算法的新方法不断涌现,如HaploPool算法和PoooL算法,其准确性、实用性均增强。

Recently China's central government has promoted public goods investment in pursuit of rural development and poverty reduction. However, the top down nature of investment planning may lead to mismatches between public goods projects and the demands of local residents. Using village- and household-level survey data, this study seeks to identify the determinants of project implementation, focusing on investments in roads, drinking water, and irrigation. Contrary to some popular perception, our results suggest symmetry between farmers' reported demand and the types of projects implemented in their villages. The relative contribution of local demand to project implementation is seen to vary, however, across different types of public goods. (JEL D71, H41, H77, P35)