Effects of High-intensity Pulsed Electric Field on Amino Acid Content in Large-leaf Pu'er Tea Variety

[Objective] This study aimed to test the effects of high-intensity pulsed electric field on the amino acid content in Pu’er tea leaves. [Method] The amino acid contents of fermented and unfermented the leaves of large-leaf Pu’er tea variety produced in Yunnan Mengku, were measured before and after the treatment with high-intensity pulsed electric field （HPEF）. [Result] The difference of amino acid contents was notable between fermented and unfermented tea leaves produced in the same year. The amino acid content of unfermented tea leaves was larger than that in fermented tea leaves. The amino acid content in tea leaves decreased over time during storage. HPEF treatment under al the conditions improved the amino acid content in tea leaves. [Conclusion] This experiment provides theoretical foundation for the application of HPEF in processing of Pu’er tea leaves.

多元文化国家的多样性及公民教育

世界各国的种族、民族、文化、语言和宗教的多样性随着新移民的到来不断丰富。这也给公民身份和公民教育这两个概念带来了新的挑战。此研究指出民族国家(nation-states)建构既能适应新人口群体又能保证国家统一之新理念的必要性。文化多元的民族国家需要在统一性和多样性中寻找平衡点。同时,文章还介绍了民族、文化、语言和宗教多样性给公民身份带来的挑战,并强调应该通过改革公民教育使学生不仅能同时具有明显的文化、国家、地区和全球身份,还能获得参与到公民生活中所需的知识与技能。

机器学习模型在股票价格时间序列分析中的应用与比较

股票市场是国度经济的主要表现,股价的走势是股票投资者存眷的核心问题。由于股票价格固有的噪声环境和相对市场趋势的较大波动性,股价的拟合和预测是一个具有挑战性的问题。本文使用了随机森林、GBDT算法、神经网络、SVM等模型对股票价格时间序列进行了拟合。