国际贸易理论研究的新动向——基于异质企业的研究

主流国际贸易理论均基于同质企业的假定来分析国际贸易的原因和影响。近年来以Melitz为代表的经济学家开始将企业异质性纳入国际贸易理论研究。本文以被Helpman称为基石性的Melitz"贸易对行业内资源配置与生产率的影响"一文为基础,介绍当前"新"贸易理论①的主要理论框架、主要观点和贸易自由化的经济效应。     

具有异质性非参数时间趋势的面板数据模型的估计

本文为一类具有异质性非参数时间趋势的面板数据模型提出了一种简单估计方法。基于局部多项式回归的思想,首先去除数据中的时间趋势成分,然后由最小二乘法来估计公共系数,同时得到时间趋势函数的非参数估计。在一些正则条件下,研究了这些估计量的渐近性质,即在时间维度T和横截面维度n同时趋向无穷时,建立了各个估计量的渐近相合性和渐近正态性。最后通过蒙特卡洛模拟,考查了这种估计方法的有限样本性质。     

On local indeterminacy and endogenous cycles in Ramsey models with heterogeneous households

It is well-known that endogenous cycles can occur in Ramsey models with heterogeneous households and borrowing constraints. In this note, we address the issue of robustness in the more general case of endogenous labor supply and we explain the occurrence of local indeterminacy under progressive taxation.

Evidence on the contrarian trading in foreign exchange markets

This paper investigates the existence and price impacts of contrarian behavior in the foreign exchange markets. By utilizing a nonlinear behavioral model where the chartists and fundamentalists coexist, evidence obtained from two sample periods significantly supports the existence of contrarian trading in the British pound, the Japanese yen and the German mark markets. The contrarian trading can only partially offset the price impacts of trend-followers, therefore the price impact of the chartists as a whole is destabilizing. The ability that the contrarians can counterbalance the extrapolation of the trend-followers differs across markets. Traders in the BP market have the highest tendency to contrarian strategy, which in turn contributes to the least deviations of the BP exchange rates departing from its PPP fundamentals. The fundamentalists' confidence in trade fades during large misalignments, which make the mean reversion function of the fundamentalists weak under the circumstances. We find the magnitudes of interventions will be affected by the price impacts of contrarians and their abilities on market stabilization.     

Putting Ethics on the Agenda for Real Estate Agents

This article uses sociological role theory to help understand ethical challenges faced by Norwegian real estate agents. The article begins with an introductory case, and then briefly examines the strengths and limitations of using legal definitions and rules for understanding real estate agency and real estate agent ethics. It goes on to argue that the ethical challenges of real estate agency can be described and understood as a system of conflicting roles with associated rights and duties, in particular sales agent, intermediary and adviser sub-roles. The arguments are developed using exploratory findings from a survey of Norwegian real estate agents and from several focus groups. The article then suggests the use of various intranet tools as a kind of action research aimed at putting ethics on the real estate agents’ agenda, working to develop a collective conscience and collective self- criticism among the agents, and, in doing so, building bridges between academic research and the practical working world of the agents.     

氟喹诺酮药物中间体合成研究进展

介绍了合成喹诺酮药物-些重要中间体所取得的新进展,这些中间体包括：2,3,4-三氟～4-硝基苯、2,4-二氯-5-氟苯甲酸、4-丁酰氯、2,6-二氯-5-氟烟酰乙酸乙酯、2,4-二氯-5-氟苯乙酮、2,4-二氯氟苯等。另外,对某些合成方法的改进作了较详细叙述,如：2,4-二氯氟苯、2,4-二氯-5-氟苯甲酸等。如其中以1,2,3-三氯苯为起始原料,经硝化、氟化两步反应制得的1,2,3-三氟-硝基苯产品质量分数大于99％,收率达60％。     

数量驱动或创新驱动：异质型人力资本对经济增长的机制演进

基于1987-2017年中国省际面板数据,运用SYS-GMM模型研究异质型人力资本对经济增长的影响。在区分高级与基本人力资本基础上,基于招生率和收入维度,从全局和阶段差异视角剖析异质型人力资本对经济提速的机制演进。研究发现：全局而言,两种测度下基础和高级人力资本各自以数量及创新方式驱动经济增长,并呈现以数量驱动为主,数量、创新双驱动的增长模式;从演进视角看,两种测度均表明,高级人力资本创新驱动是新常态阶段经济增长的核心动力,但相比旧常态阶段,基础人力资本数量驱动日趋弱化并呈异质性;进一步研究表明,产业结构、城镇化及开放程度均对创新驱动有不同程度激励效应,而城镇化是挤出数量驱动的主要推手。     

Design of Digital Agricultural Extension Tools: Perspectives from Extension Agents in Nigeria

Given the marked heterogeneous conditions in smallholder agriculture in Sub-Saharan Africa, there is a growing policy interest in site-specific extension advice and the use of digital extension tools to provide site-specific information. Empirical ex-ante studies on the design of digital extension tools and their use are rare. Using data from a choice experiment in Nigeria, we elicit and analyze the preferences of extension agents for major design features of ICT-enabled decision support tools (DSTs) aimed at site-specific nutrient management extension advice. We estimate different models, including mixed logit, latent class and attribute non-attendance models. We find that extension agents are generally willing to use such DSTs and prefer a DST with a more user-friendly interface that requires less time to generate results. We also find that preferences are heterogeneous: some extension agents care more about the effectiveness-related features of DSTs, such as information accuracy and level of detail, while others prioritise practical features, such as tool platform, language and interface ease-of-use. Recognising and accommodating such preference differences may facilitate the adoption of DSTs by extension agents and thus enhance the scope for such tools to impact the agricultural production decisions of farmers.     

Destination management organizations and destination marketing: adopting the business model of e-portals in engaging travel agents

ABSTRACT

Destination management organizations (DMOs) have an important role in engaging stakeholders in collaboration. Collaborating with stakeholders is useful for both stakeholders and destinations. However, it takes time and needs rigorous coordination to avoid conflicts with stakeholders. This study measures travel agencies’ attitudes towards engaging in online collaboration with DMOs for marketing purposes. It incorporates collaboration and technology acceptance models to predict the attitudes and intentions of travel agents using structural equation modeling. Data were collected from travel agents in Cairo, Egypt, using the random sample technique. This study will be useful for travel and tourism stakeholders and governmental marketing bodies.     

Neutral agents and social tolerance: a dynamic perspective based on economic interaction model with local social cost functions

The influence of neutral agents on the evolutionary dynamics of social tolerance is discussed based on a recently proposed economic interaction model with local social cost functions. We show that the dynamical structure of social tolerance is completely changed even if a few neutral agents are introduced into the society. Especially, the full intolerance steady state, which is stable in previous works, becomes unstable and avoidable due to the economic incentive introduced by the neutral agents. The necessary condition of achieving full tolerance is also reduced compared to previous works without neutral agents.