The potential of participatory hybrid breeding

This article explores the potential of involving smallholder farmers in hybrid development for their low-external input farming systems. We have developed a conceptual model of the procedures, based on five assumptions: (a) the hybrids are bred for adaptation to local needs and preferences; (b) the dependence on and need for genetic diversity is taken into account; (c) breeders collaborate closely with farmers also in the initial stages of the breeding programme, that is, in establishing the breeding goals by identifying the desired traits and preferred local populations as (one of the) crossing parents; (d) hybrid seed production can be integrated into the farmers’ local seed system; and (e) farmers and breeders can agree on intellectual property rights, access and benefit sharing in a fair and transparent way. We illustrate the procedural consequences of these assumptions with reference to the case of a participatory maize breeding programme in southwest China, from 2000 to 2012, that included both open-pollinated and hybrid maize improvement. We show how farmers’ early involvement in hybrid development during the pre-breeding stage, including broadening the base populations with farmer-maintained local landraces, can support co-evolution of the genetic resources in farmers’ fields.     

边缘省区县域经济差异的空间格局演化分析——以广西为例

以县域为研究单元,人均GDP为测度指标,运用ESDA-GIS方法对1997—2010年处于全国经济边缘的广西区内空间差异格局进行分析,发现其县域经济已初现较为显著的空间自相关,发展差异呈现出先扩大后缩小的趋势,但总体空间集聚水平仍较低。在局部差异方面,高—高类型区集中在桂南县域及柳州、桂林中心城区,低—低类型区集中在桂西及桂中县域。受空间相互作用影响,边缘省区内核心—外围结构显著。经济热点区在保持总体格局相对稳定的情况下有进一步向桂南沿海的北部湾经济区集聚的趋势。经济增长也具有较强空间关联特征,热点区和冷点区快速跃迁,增长的空间差异缓慢缩小。进而,从历史发展基础、地理区位、开放开发政策和空间邻近效应等方面讨论了边缘省区经济空间差异的动因与政策启示。     

高层结构施工应注意的几个问题

针对铜陵地区特殊的地质条件,文章就高层建筑地下室地基土方施工应注意的问题,以及本地区高层建筑施工中混凝土施工缝留设、地下室混凝土壁板抗渗、钢筋施工、混凝土界面处理等方面常见的问题及处理措施进行了分析。     

Value-at-Risk under Measurement Error

We propose a method for estimating Value-at-Risk that corrects for the effect of measurement errors in stock prices. We show that the presence of measurement errors might pose serious problems for estimating risk measures. In particular, when stock prices are contaminated, existing estimators of Value-at-Risk are inconsistent and might lead to an underestimation of risk, which can result in extreme leverage ratios within the held portfolios. Using a Fourier transform and a deconvolution kernel estimator of the probability distribution function of actual latent prices, we derive a robust estimator of Value-at-Risk in the presence of measurement errors. Monte Carlo simulations and real data analysis illustrate satisfactory performance of the proposed method.     

Liquidity and Twin Crises

This paper proposes a simple analytical framework for understanding 'twin crises'– i.e. crises where a currency crisis and banking crisis occur simultaneously and reinforce each other. The distinguishing feature of such crises is the spill‐over effects across financial institutions through collateral constraints, declines in market values of assets, currency mismatches on the balance sheet and the endogenous amplification of financial distress through asset sales. We explore the role of liquidity and the role of monetary policy in such crises. In particular, a central question is whether raising interest rates in the face of a twin crisis is the appropriate policy response. Raising interest rates has two countervailing effects. Holding the domestic currency becomes more attractive (other things being equal), but the value of the domestic banking system falls due to the fall in asset prices. When assets are marked to market, there is a potential for endogenously generated financial distress that leads to a collapse of asset prices, as well as the exchange rate. It is thus possible that raising interest rates can have the perverse effect of exacerbating both the currency crisis and the banking crisis.     

Forecasting UK house prices: A time varying coefficient approach

Previous studies of UK house prices, developed from the demand and supply ofhousing or from the asset market approach have been poor in terms of robustness and ex-post forecasting ability. The UK housing market has suffered a number of structural changes, particularly since the early 1980s with substantial house price increases, financial market deregulation and the removal of mortgage market constraints through competition. Consequently, models which assume that the underlying data-generating process is stable and apply constant parameter techniques tend to suffer in terms of parameter instability. This article uses the Time Varying Coefficient (TVC) methodology where the underlying data-generating process in the UK housing market is treated as unstable. The estimation results of the TVC regression of UK house prices is compared with those obtained from three alternative constant parameter regressions. Comparisons of forecasting performance suggest the TVC regression out-performs forecasts from an Error Correction Mechanism (ECM), Vector Autoregressive (VAR) and an Autoregressive Time Series regression.     

我国货币政策区域效应的存在性及原因--基于最优货币区理论的分析

早在蒙代尔提出最优货币区理论之时,他就指出了最优货币区的范围可以大于国界,也可以在一国国界之内。本文把常用于国际经济领域的最优货币区理论运用于我国这样一个大国内部,指出我国并不满足最优货币区标准;利用VAR模型和IRF检验也证实我国货币政策存在显著的区域效应。进一步,本文从货币政策传导机制的角度分析得出信贷渠道和利率渠道是导致我国货币政策区域效应的主要原因。最后本文提出推进生产要素自由流动,缩小东中西区域经济差异,顺畅我国货币政策传导机制的建议。     

推进“中部崛起”的思路与对策——著名经济学家樊纲访谈录

2006年新年伊始,著名经济学家、中国经济体制改革研究基金会秘书长樊纲教授应邀来安徽出席“2006安徽财富论坛”,并发表了有关“中部崛起”的学术演讲。笔者在此期间就此主题访问了樊纲教授。     

掌握农村金融需求特点,推进农村金融体制改革

农村资金缺乏严重地制约着农业和农村经济发展,必须要加快农村金融体制改革。农村金融需求有着与城市金融需求不相同的特点,因此,农村金融体制改革要按农村金融需求特点进行。当前,农村金融体制改革必须在发展农村金融组织、转换农村信用社经营机制、加大对农村金融机构扶持力度方面有所突破,从而更好地服务于“三农”。     

对我国区际经济与金融差距关联性的实证分析

各区域间金融发展的差异对经济发展差距有无影响以及影响机制如何成为经济学研究的一项任务。以塞尔指标衡量我国经济与金融发展差距,发现我国区域间经济发展差距与金融发展差距呈现一致的变动关系,且金融差距大于经济差距。由此引出的基本判断是我国区际经济差距的逻辑原因有金融因素,进而采用格兰杰因果关系检验判断我国省际金融发展与经济增长间的关系,从中可以明确我国东部地区金融成长偏重于内生状态,而中西部地区更倾向于外生状态。考虑到改革的总体方向,并借鉴东部地区的经验,放松金融抑制、催化内生金融成长无疑是全面促进中西部经济发展的必然选择。