干旱影响生计脆弱性中的中介和调节效应

［目的］气候变化下跨尺度变量对生计脆弱性的影响多数为定性研究，很少进行实证研究，文章通过实证分析探索跨尺度变量在干旱影响生计脆弱性中的作用。［方法］基于黄土高原218个农户调查数据，采用线性回归和层次回归分析跨尺度变量在干旱影响生计脆弱性中的中介和调节效应。［结果］干旱对农户生计脆弱性有显著影响。在干旱影响生计脆弱性的过程中，个人尺度的“户主年龄、感知的气温最大值、降雨量变化、干旱程度变化和灾后信息渠道”与农户尺度的“批发市场距离和集市距离”起到了调节作用； 农户尺度的“三代直系亲属的户数和生产机械指数”起到了中介作用； 而村庄尺度的“工程措施”，既没起到中介作用，也没起到调节作用。［结论］用中介和调节效应反映了跨尺度变量的交互作用，在跨尺度效应的实证研究方面提供了科学的方法，弥补了现有研究的空白，这为制定减少农户生计脆弱性的政策提供了科学有效的依据。     

Assessing effects of federal crop insurance supply on acreage and yield of specialty crops

Crop insurance may affect harvested acreage and yield by influencing producers’ behavior such as land allocation and input use. Although specialty crops are a major source of farm income, especially on the U.S. west coast, they have not received as much attention as field crops in previous empirical studies. This paper assesses the effect of moral hazard and adverse selection associated with the federal crop insurance program (FCIP) on the acreage and yield of major specialty crops in California. An econometric method that expands the switching regression model is developed to assess the effect. Results suggest that federal crop insurance can change specialty crop growers’ production responses to climate and soil conditions. The moral hazard effect tends to increase the acreage and yield of the specialty crops, whereas the adverse selection effect tends to have the opposite effect. The overall effect of the FCIP on acreage and yield of specialty crops is found to be moderate.     

Budget impact analysis of niraparib and olaparib for maintenance treatment of platinum-sensitive,recurrent ovarian cancer in the US

Aims: This study aimed to evaluate the budget impact of niraparib and olaparib in patients with platinum-sensitive, recurrent ovarian cancer from a US third party payer perspective.

Materials and methods: A budget impact model was constructed to assess the additional per member per month (PMPM) costs associated with the introduction of niraparib and olaparib, two poly ADP-ribose polymerase ribose polymerase (PARP) inhibitors recently approved to be used in platinum-sensitive, recurrent ovarian cancer patients with and without a gBRCA mutation. The model assessed both pharmacy costs and medical costs. Pharmacy costs included adjusted drug costs, coinsurance, and dispensing fees. Medical costs included costs associated with disease monitoring and management of adverse events from the treatment. Epidemiological data from the literature were used to estimate the target population size. The analysis used 1-year time frame, and patients were assumed on treatment until disease progression or death. All costs were computed in 2017 USD. One-way sensitivity analyses were conducted to evaluate the model robustness.

Results: In a hypothetical plan of 1,000,000 members, 206 patients were estimated to be potential candidates for niraparib or olaparib maintenance treatment after applying all epidemiological parameters. At listed 30-day supply WAC prices of $14,750 for niraparib and $13,482 for olaparib, budget impacts of these two drugs were $0.169 PMPM and $0.156 PMPM, respectively, most of which were contributed by pharmacy costs. Sensitivity analyses suggested that assumptions around market share, platinum-sensitive rate after first treatment, and WAC prices affected results the most.

Limitations: In this model, it was assumed that adopting niraparib and olaparib would not affect utilization of existing medications. Also, the estimated clinical parameters from clinical trials could differ from real-world data.     

Remaking Shanghai: New Divisions in an Expanding Metropolis

This study of Shanghai analyzes the city's emerging patterns of residential settlement in 2010. Most previous research on China focused on central city patterns, but by 2010 urban development in major metropolitan areas was taking place predominantly in the suburbs. The analysis re‐examines and extends previous studies of the level of segregation by various key population characteristics, showing that the highest segregation is found in the suburban ring, where original villager residents are now joined by an influx of migrants from other regions and by intracity movers. We probe the sources of the segregation pattern in multivariate analyses at two scales—an innovative analysis at the level of individuals that shows how people's citizenship status, occupation and education affect the type of housing that they are able to live in, and jointly contribute to their location in the metropolitan area. We show that the patterns attributable to the market reform period mostly did not supplant the socialist urban structure, but rather used it as its foundation. Segregation today can be attributed less to current class inequality than to state policies in the distant and recent past that have determined when, where and for whom housing is built.     

Moral hazard and subsidized crop insurance

Along with adverse selection, moral hazard is one of the major hurdles that private and public insurance plans must contend with. Moral hazard occurs if risks are endogenous to a producer's behavior and if the insurer is unable to properly monitor the insured. We review the role of moral hazard in the US crop insurance program. We conduct an empirical analysis of one important aspect of the US crop insurance program—prevented planting. This provision provides indemnity payments if conditions are not suitable for planting. The program has been the subject of considerable controversy, especially during 2019, when the rate of claims is expected to be especially high. Because loss adjustors may encounter difficulties in assessing the weather conditions associated with prevented planting claims, the program is susceptible to moral hazard. We consider the extent to which prevented planting claims may be endogenous to prices. We find significant evidence of moral hazard. The likelihood of prevented planting claims increases as the expected market price decreases or as fertilizer costs increase for corn and soybeans in the Prairie Pothole Region and for grain sorghum and cotton in all states.     

企业主导创新社区用户参与和新产品创意产出的动态关联研究

基于用户视角研究企业主导创新社区用户参与和新产品创意产出的动态关系。在理论分析的基础上，利用方差分析实证检验新产品创意产出不同阶段用户参与的变化。以12个社区共2400名用户为研究对象的实证结果表明：伴随创意产出数量的阶段提升，用户参与广度和深度都逐渐提高；伴随创意产出质量的阶段提升，用户参与深度逐渐提高，而用户参与广度只在创意产出质量后半阶段有显著提高。研究结果对我国消费电子企业动态采取措施引导用户参与创新有一定指导意义。     

我国水稻产业供给侧结构性改革的思考

[目的]文章在供给侧改革视角下对水稻供需的结构性矛盾等方面进行梳理,分析基于供给侧改革战略的关键环节、实施路径和未来发展趋势,以期为制定我国水稻供给侧改革战略提供参考。[方法]采用文献分析法和调查研究法,从我国水稻生产供求结构、价格"天花板"和成本"地板"双重挤压、水稻生产的资源环境、市场调节等方面分析了我国水稻产业供给侧的现状和存在的问题;通过日本、泰国、中国五常大米政策特点和经验教训的启示,提出了我国水稻产业供给侧结构性改革的策略。[结果]在分析我国水稻产业供给侧现状的基础上,总结得出水稻产业供给侧改革措施:优化水稻产业空间和功能布局,以项目带动水稻产业结构调整,提高和优化稻米品种品质结构、审定标准向抗性优质专用水稻品种倾斜,因地制宜调减水稻生产面积,调整国家收储稻米标准,延长水稻全产业链等。[结论]加速我国水稻产业供给侧改革,能促进稻米产业结构快速升级,有效破解稻米产业的结构性矛盾,增强我国稻米产业可持续发展能力和国际竞争力。     

湖南省乡村建设水平评价及对景观的影响利弊

［目的］改善乡村人居环境，推动新农村建设，是全面建设小康社会的重要组成部分。［方法］从经济发展水平、生活质量水平、社会发展水平及生态发展状况等4个方面构建包括20个指标在内的评价体系，基于2007—2017年的统计数据，采用熵权法对湖南省乡村建设水平进行定量化测度。在此基础上，进一步阐述了乡村建设对乡村景观影响的利弊。［结果］湖南省乡村建设发展水平评价分值呈现显著的递增趋势，由2007年的0177提高到2017年的0692。其中经济发展水平、生活质量水平、社会发展水平均明显提升，但生态发展状况波动较大，虽近年来得到一定的控制，但仍是制约新农村建设的重要因素。新农村建设为乡村景观的规划提供了经济支持，改善了乡村景观基本硬件设施条件，乡村旅游产业的发展也丰富了乡村景观的形式内容，推动了乡村景观的建设，但也在一定程度上引发了对生态系统平衡的破坏和对乡村景观的蚕食。［结论］在新农村建设过程中，遵循生态理论，充分体现地域特色，科学合理地进行乡村景观规划对推动新农村建设水平的整体提升至关重要。     

数字经济下的转换成本对市场竞争的影响分析

转换成本可以通过市场力量和企业的策略性行为对市场竞争产生重要影响,因此成为竞争执法机构竞争评估的重点考察因素,而当前数字经济具有的网络效应和多归属等特征使得转换成本对市场竞争的影响更加复杂。本文首先从经济学角度剖析转换成本的定义、起源与分类,而后考察转换成本与网络效应和多归属之间的关系,最后研究转换成本对市场竞争的影响、系统论述转换成本在数字经济下可能引起的竞争关注。     

人工智能在我国公共卫生建设中的应用与思考

新冠疫情的暴发以及长期防治对中国的公共卫生体系造成深远影响，给我国突发公共卫生事件应急与防控机制带来巨大的考验。在疫情防控的过程中，信息化技术为传统医疗机构带来瞩目的帮助与改变，人工智能、大数据、5G高速网络等新兴高科技的蓬勃发展在直接提升医疗水平方面表现出巨大潜力。本文就人工智能在疫情期间的医疗辅助功能展开讨论，并对未来我国公共卫生体系的建设进行了思考。