Neutral Community Theory: How Stochasticity and Dispersal-Limitation Can Explain Species Coexistence

Neutral community theory explains biodiversity, i.e. the coexistence of several species, as the result of a stochastic balance between immigration and extinction on a local level, and between speciation and extinction on a regional level. The most popular model, presented by Hubbell in 2001, has seen many analytical developments in recent years, which can be used in model analysis, model testing and model comparison. We review these developments here, and present alternative derivations and shine previously unnoticed lights on them.     

浙江发展会展旅游的战略构想

通过对浙江会展旅游现状的分析和研究,总结了浙江会展旅游业的现状与优势,指出了面临的问题,进而从政府与会展企业角度提出了发展浙江会展旅游业的对策.     

A safe minimum standard,the elasticity of substitution,and the cleanup of the Ganges in Varanasi

Despite repeated calls for a thorough cleanup of water pollution in the Ganges river, there are only two papers in the social sciences by Batabyal and Beladi (2017, 2019) that have shed theoretical light on this cleanup problem and its connection to the sustainability of tourism in Varanasi. Hence, we extend the above‐mentioned analyses and focus on two specific questions. First, we introduce the notion of a safe minimum standard (SMS) into the study and show how to analyze a probabilistic model of the Ganges cleanup problem when the SMS is accounted for. Second, for a representative citizen of Varanasi, we study how the magnitude of the elasticity of substitution between a composite consumption good and water quality in the Ganges—modeled by the SMS—affects the tradeoff between consumption and water quality maintenance.     

Families,experiments, and nature: Learning science through project-based learning

This study brings together the research focused on science education through project-based learning (PBL). This learning project was carried out in a rural learning community and an attempt was made to adapt to the natural resources of the area by organizing educational outings, experimental activities, and encouraging the participation of families. The overall objective is to test the effectiveness of applying the PBL teaching methodology for learning science in a rural learning community. The methodology used has been qualitative, specifically, the participating research has been used and the information has been compiled in a field notebook. The results show that the didactic proposal had good results; showing that, in conclusion, science teaching today should be inclined toward more innovative educational methodologies such as PBL.     

基于不同条件的旅游路线规划问题研究

运用2015年全国研究生数学建模竞赛F题的数据资料,针对旅游路线合理规划问题的第一问展开研究.以F题的问题一为起点进行了分析研究,是因为第一问的完成是解决后续问题的关键.首先通过地图搜集并补全了缺失数据并对数据进行合理的处理,然后采用将旅游年数最少目标转化为该最小生成树的"最少圈覆盖"方法来进行对问题一的求解,也可以理解为一个广义的多旅行商问题,以旅行商的人数(即年数)最少为目标.采用Dijkstra算法、最少圈覆盖法、智能算法和图论聚类等方法,通过这些方法建立了单目标优化模型,并运用旅行商问题和模型之间的转换来对问题进行分析与求解.     

论卤盐养生（8）

卤盐（包括食盐）是中国矿物药的重要组成部分。从文化价值、临床应用和情志调摄3个方面诠释了卤盐的养生学意义,并全面、详细地阐述了食盐对中国古代文化的四大贡献、6种盐类的现代临床应用价值以及盐湖旅游的6项要素;列举了160多个盐湖卤水的主要化学成分、矿化度或微量元素;摘录了论述卤盐主治功用的古今文献。本文分期刊出。     

论卤盐养生（10）

卤盐（包括食盐）是中国矿物药的重要组成部分。从文化价值、临床应用和情志调摄3个方面诠释了卤盐的养生学意义,并全面、详细地阐述了食盐对中国古代文化的四大贡献、6种盐类的现代临床应用价值以及盐湖旅游的6项要素;列举了160多个盐湖卤水的主要化学成分、矿化度或微量元素;摘录了论述卤盐主治功用的古今文献。本文分期刊出。     

Positive Effect of Ecological Restoration with Fabaceous Species on Microbial Activities of Former Guyanese Mining Sites

Understanding ecological trajectories after mine site rehabilitation is essential to develop relevant protocols adapted for gold mining sites. This study describes the influence of a range of mine site rehabilitation and revegetation protocols on soil physicochemical parameters and microbial activities related to carbon, nitrogen and phosphorus cycles. We sampled soil from six rehabilitated mining sites in French Guiana with different plant cover (herbaceous, Cyperaceous, monoculture of Clitoria racemosa and Acacia mangium and association of C. racemosa and A. mangium). We measured the mineralization potential of organic matter by estimating the mineralization of carbon, nitrogen and phosphorus and the microbial catabolic diversity balance. The results showed an improvement in the quality of organic matter on revegetated sites with tree cover. On restored sites with fabaceous species, the microbial biomass is three times higher than non-restored sites, improving the rates of organic matter mineralization and restoring the catabolic diversity to the level of natural Guyanese soils. These results confirm that the establishment of fabaceous species under controlled conditions significantly improves the restoration of microbial communities in mining soils.     

游客情感计算的文本大数据挖掘方法比较研究

旅游文本大数据以其方便、快捷和低门槛的特点为游客情感计算提供了极大便利,已经成为旅游大数据的主要来源之一。基于大数据理论和情感理论,以文本大数据为数据源,在全面梳理国内外情感计算相关成果的基础上,利用人工智能中的逻辑/算法编程方法、机器学习方法、深度学习方法对旅游文本大数据进行挖掘,探索最佳的基于文本大数据的游客情感计算方法。研究发现：（1）基于情感词典的游客情感计算模型,其核心是构建情感词典和设计情感计算规则,方法简单,容易实现,适用语料范围广。（2）机器学习,用统计学方法抽取文本中的特征项,具有非线性特征,可靠性较线性特征的情感词典方法高。（3）基于深度学习技术的游客情感计算,效果良好,准确率在85%以上。训练多领域的文本语料易于移植,实用性强,且泛化能力好,较适合大数据时代游客情感计算研究。     

Phylogenetic characterization of a mixed microbial community capable of degrading carbon tetrachloride

Two bacterial communities (NO92 and GBS) capable of degrading carbon tetrachloride (CT) were enriched from in-house CT-contaminated water. These communities are able to degrade CT in the presence of toluene. To characterize the community structure and diversity, one enrichment (NO92) was subjected to 16S ribosomal RNA (rRNA) gene-based molecular analysis. The 16S rRNA genes were amplified from the bulk genomic community DNA and cloned into plasmid vectors. Unique 16S rRNA gene clones, i.e., phylotypes, were detected by four tetrameric restriction enzymes. Together, 123 16S rRNA gene clones were obtained; thirty-one showed different restriction fragment length polymorphism (RFLP) patterns. About 73% of the clones belong to two dominant RFLP patterns. Phylogenetic analysis based on the partial 16S rRNA gene sequences of 10 major phylotypes showed that all the phylotypes that were sequenced were affiliated with the high G+C Gram-positive bacteria. Whereas seven of the phylotypes (∼80% of the clones) were closely related to Rhodococcus, the other three (∼5% of the clones) were related to Curtobacterium. These results suggest that this CT-degrading community is diverse but is predominated by closely related bacterial groups.