A Bayesian Regression Model and Applications

A sparse vector regression model is developed. The model is established by employing Bayesian formulation and trained by using a set of data <img src="Edit_c3ff10a2-e8b8-4862-bc9d-74ca04016ecb.bmp" alt="" />. The parameters needed to be determined in the algorithm are reduced by a special prior hyperparameter setting, and therefore the algorithm is simpler than similar type of Bayesian vector regression models. The examples of applications to the function approximation and inverse scattering problem are presented.

Responses of soil microbial communities to manure and biochar in wheat cultivation of a rice-wheat rotation agroecosystem in East China

Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.

人工智能辅助会话式编程：一种性别包容的程序设计教学法

由于对计算机科学和职业的陌生和畏惧,技术落伍群体认识不到与真实世界之间存在的联系,使得将计算机程序设计教学普及到这些群体成为近年来的一项挑战。英国开放大学等机构通过使用技术手段设计开发教育类游戏等方式在STEM领域扩大学生参与度,使技术落伍群体(包括很多女性)提高对计算机编程的兴趣。本文使用以亚马逊语音技能工具包(ASK)为代表的人工智能工具,让学生通过语音会话式交互学习程序设计技术,探讨了如何把序列性会话转换为层次性决策树驱动的交互会话,提供了一种基于知识图谱的教学法,通过个人软件助理——"大声说程序"(Ask Program Aloud)引导人机对话。通过具体案例和用户参与,定性评估了使用"大声说程序"发起对话这个方法的有效性。结果表明,人工智能确实能够提升参与者对学习计算机编程技能的兴趣,既可以支持目前单向会话形式的计算机编程教学,也可以鼓励技术相对落伍的学习者群体获得计算机编程能力,进一步提高社交友好性和技能转化能力。

水稻镉积累特性的生理和分子机制研究概述

我国的稻米镉超标对国民身体健康造成严重威胁,而选育低镉积累的水稻(Oryzasativa)品种是降低稻米镉含量行之有效的策略,因此有必要了解水稻对镉的积累特性及其生理过程和相关功能基因。该文概述了镉在水稻根部的吸收、木质部中的装载与运输、茎节中的分配、叶片中再分配以及籽粒镉积累等过程的生理和分子机制研究进展,以期为低镉水稻的选育和安全生产提供理论参考。

Assessment of the sources and transformations of nitrogen in a plain river network region using a stable isotope approach

The great spatial and temporal variability in hydrological conditions and nitrogen（N）processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regions. By combining isotopic data with chemical and hydrologic measurements, we determined the relative importance of N sources and biogeochemical N processes in the Taige River in the East Plain Region of China. The river was polluted more seriously by anthropogenic inputs in winter than in summer. Manure and urban sewage effluent were the main nitrate（NO-3） sources, with the nitrification of N-containing organic materials serving as another important source of NO-3. In the downstream, with minor variations in hydrological conditions, nitrification played a more important role than assimilation for the decreasing ammonium（NH＋4-N） concentrations.The N isotopic enrichment factors（ε） during NH＋4utilization ranged from- 13.88‰ in March to- 29.00‰ in July. The ratio of the increase in δ^18O and δ^15N of river NO-3in the downstream was 1.04 in January and 0.92 in March. This ratio indicated that NO-3assimilation by phytoplankton was responsible for the increasing δ^15N and δ^18O values of NO-3in winter. The relationships between δ^15N of particulate organic nitrogen and isotopic compositions of dissolved inorganic nitrogen indicated that the phytoplankton in the Taige River probably utilized NH＋4preferentially and mainly in summer, while in winter, NO-3assimilation by phytoplankton was dominant.

Emission tunable of Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35):Eu^(2+),Mn^(2+) oxynitride phosphors via energy transfer for WLEDs

A series of Eu^(2+)doped and Eu^(2+)/Mn^(2+) co-doped Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35)(MSAON) phosphors were synthesized by solid-state reaction at a lower temperature of 1500℃.The crystal morphology and structure of MSAON host were characterized by SEM,TEM and XRD.The quantum yield(QY) for Eu^(2+)doped MSAON phosphors was measured as high as 62%,indicating the excellent luminous efficiency.For the Eu^(2+)/Mn^(2+)co-doped MSAON phosphor,the photoluminescence spectrum and delay curves reveal the efficient energy transfer(ET) process from Eu^(2+)to Mn^(2+)ions.Meanwhile,the corresponding energy transfer efficiency,critical distance and mechanism are discussed in detail.Temperature-dependent emission spectrum shows the thermal and color stabilities.The emission color of MSAON:Eu^(2+),Mn^(2+)phosphors could be tuned from blue through white to red via varying the concentration of Mn^(2+) ions.White-light-emitting diodes(WLEDs) were successfully fabricated by encapsulating the phosphors in nUV LED(365 nm) devices obtaining white light with color rendering index(CRI) as high as 87.7.The results reveal that the MSAON:Eu^(2+),Mn^(2+)phosphors could have potential application in the field of n-UV WLEDs.