Dial “A” for agriculture: a review of information and communication technologies for agricultural extension in developing countries

Agriculture can serve as an important engine for economic growth in developing countries, yet yields in these countries have lagged far behind those in developed countries for decades. One potential mechanism for increasing yields is the use of improved agricultural technologies, such as fertilizers, seeds, and cropping techniques. Public sector programs have attempted to overcome information‐related barriers to technological adoption by providing agricultural extension services. While such programs have been widely criticized for their limited scale, sustainability, and impact, the rapid spread of mobile phone coverage in developing countries provides a unique opportunity to facilitate technological adoption via information and communication technology (ICT)‐based extension programs. This article outlines the potential mechanisms through which ICT could facilitate agricultural adoption and the provision of extension services in developing countries. It then reviews existing programs using ICT for agriculture, categorized by the mechanism (voice, text, internet, and mobile money transfers) and the type of services provided. Finally, we identify potential constraints to such programs in terms of design and implementation, and conclude with some recommendations for implementing field‐based research on the impact of these programs on farmers’ knowledge, technological adoption, and welfare.     

Birthplace favoritism and the distribution of budget amendments in Brazil: Evidence from nondistrict elections

In this paper, we investigate whether federal deputies in Brazil display birthplace favoritism in allocating discretionary resources to municipalities via budgetary amendments. The data include information on three electoral cycles and on more than five thousand municipalities. Unlike previous research, we match data on an elected deputy’s share of votes by municipality and the value of the legislative amendments per capita obtained for each municipality by that deputy. Our results suggest that although resource distribution through amendments is smaller than targeted pork spending, birthplace favoritism is still an important driver of local politicians’ behavior. On average, when a Brazilian municipality is the place of birth of a deputy, it obtains 8.7% more amendments per capita than its counterparts. Additionally, our findings suggest that some deputies display birthplace favoritism because they plan to run for mayor in their hometown in subsequent elections.     

基于VHDL利用PS/2键盘控制的密码锁设计

介绍了一种基于FPGA芯片的电子密码锁设计方法,阐述了系统各模块的功能,给出了关键的VHDL程序。系统利用了标准PS/2键盘作为输入设备,取代了普通的矩阵式键盘,展示了FPGA在嵌入式系统设计中的优越性。     

Social security and economic integration

This letter analyzes the impact of economic integration on capital accumulation and capital flows when countries differ in their social security systems. Funding and early retirement both foster capital accumulation relative to pay-as-you-go pensions with flexible retirement. When economies integrate, both imply capital outflow possibly resulting in utility losses.     

铝及铝合金宽温阳极氧化工艺

介绍一个添加了LK-2添加剂的铝合金硫酸阳极氧化工艺,该工艺对用铸铝合金和硬铝合金材料制作的汽车配件进行了10年的实际生产考核验证,证明该工艺不需配置冷冻降温措施,一年四季均可进行连续生产。所生成的铝合金氧化膜性能较好,不会出现过腐蚀起粉现象。与传统硫酸阳极氧化工艺相比,大大降低了设备投资和生产的能耗成本。     

P2P网络资源发现方式探析

P2P是一种依赖网络中参与者的计算能力和带宽而不把依赖都聚集在较少的几台服务器上的网络技术。简单介绍了集中式、混合式、无结构化分布和结构化分布四种体系结构下流行的P2P网络的资源发现方式,通过实例分析了各体系下的典型应用并总结了各自的优缺点。     

校园网P2P流量控制方法与实践

P2P（Peer to Peer,对等网）技术采用＂无集中服务器＂工作模式,能充分利用大量在线客户端设备（如PC机等）的资源而优化文件传输的能力。P2P应用消除了服务器瓶颈,但也导致网络带宽资源的极大消耗。校园网网络出口由于受到带宽的限制,P2P应用的增加,势必导致非主要网络应用引起带宽挤占和延迟的增大,在不进行有效管理与控制的条件下,将严重影响正常的网上办公教学。文章在分析各类流量控制方法利弊的基础上,以某高校为例,讨论在校园网中进行P2P流量控制的方法与步骤。     

安塞油田塞152区块井筒防腐工艺研究

安塞油田塞152区块开采长2油层,由于产出液腐蚀性强,致使井筒内油管穿孔、油杆断裂等现象时有发生,井下维护性作业频繁,严重影响油井的正常生产。研究认为硫化氢与二氧化碳共同作用引起的局部腐蚀是该区块井筒腐蚀的主要原因。通过筛选适合长2流体性质的缓蚀剂和采用从套管环空人工定期投加的工艺,井筒腐蚀得到有效控制,延长了油管杆的使用寿命,大幅减少了油井维护性作业井次。     

Insider ownership and firm performance: An examination of restaurant firms

This study investigated the relationship between insider ownership and firm performance in the restaurant industry. Convergence-of-interests and entrenchment hypotheses were tested via cross-sectional and panel two-stage least square (2SLS) GMM estimation methods for linear and non-linear models. The study found that there is an overall positive and significant relationship between insider ownership and firm performance. The quadratic model showed that restaurant firm performance increased until insider ownership was between 38 and 40%, whereas it decreased after that point. Consistent with the quadratic model, the piece-wise regression model showed that insider ownership had a positive impact on firm performance within a range of 5–25% and a negative influence beyond 25% insider ownership. Consequently, this study revealed that convergence-of-interests and entrenchment effects of insider ownership co-exist in the restaurant industry. While convergence-of-interests effects are effective, an excessive granting of stock options or awards to managers could weaken firm performance due to entrenchment effects.     

二氧化钛光催化降解水中污染物性能研究

环境污染引起人们对更多环保技术的关注和研究。TiO2光催化氧化作为一种高级氧化技术,其氧化能力强,催化活性高,生物、化学、光化学稳定性好等优势一直是光催化研究的热点。本文综述了TiO2降解污染物的机理、影响因素以及现在研究的主要方向和工业化发展需要取得的突破。