近60年长江流域河流纵向连通性演变特征

以长江流域为研究区,基于流域内水库、水电站、水闸和橡胶坝等4类拦河建筑物建设情况,采用阻隔系数法、最长连续河段占比法和区域整体法3种评价方法,探究近60年长江流域河流纵向连通性的演变特征。结果表明：基于阻隔系数法和最长连续河段占比法,2018年长江流域45条主要河流中评价等级为差、劣的河流数量皆为30条;在时间维度上,近60年长江流域主要河流的纵向连通性呈逐渐恶化的趋势,其中2000—2018年纵向连通性恶化最为显著;在空间分布上,评价等级为劣的主要河流集中分布在岷沱江、嘉陵江和洞庭湖水系水资源二级区;基于区域整体法,2000—2018年是长江流域二级区河流纵向连通性整体恶化的时期,2018年长江流域12个水资源二级区中有5个二级区的河流纵向连通性评价等级为优、良,其余7个二级区评价等级为中、差和劣。研究结果可为长江流域河流生态系统的保护修复提供参考。     

水库变动回水区分汊型河道河型转化研究

本文以三峡水库变动回水区青岩子河段金川碛汊道为研究对象,通过概化模型试验,结合有关的泥沙模型试验资料,分析了水库变动回水区分汊型河道河型转化各阶段的冲淤演变过程、水流结构及水力要素的变化。在此基础上阐明了河型转化的规律性,提出了引起水库变动回水区大幅度悬移质累积性淤积的临界壅水水深。     

我国区域金融成长差异的态势:1978-2003年

根据1978-2003年的有效数据,对我国的金融成长差异进行实证分析和计量检验的研究结果表明,这期间并不存在区域金融成长差异的倒U形曲线,而是呈现三次曲线的变动态势,从更长时期看,倒U形曲线是否成立还未有定论,需要多方面指标的比较和未来时间的检验,但是区域金融成长的非均衡是长期存在的,这个结论同时也得到了演化经济理论的有力支撑,因此我国区域金融成长不能过度强调趋同,应该适度差距、系统优化、协调发展。     

How does the geographic export diversification–performance relationship vary at different levels of export intensity?

We argue that the relationship between geographic export diversification and firm performance follows an S-curve relationship if export intensity is low and an inverted U-shape if export intensity is high. The S-shape curve occurs because firms have weaker incentives to deploy the resources needed for succeeding in foreign markets if they generate relatively low revenues in export markets compared to their domestic market. Firms highly committed to export markets, in contrast, face stronger incentives to accelerate their learning curve, which results in an inverted U-shape relationship. We examine our hypotheses using a panel of longitudinal archival data with over 2000 firm-year observations, which cover all of the possible export destination countries served by large Brazil-based exporters from 2001 to 2010. Our results imply that the degree of export intensity changes the cost-benefit relationship of geographic export diversification.     

蒋家沟入汇河段泥石流堆积与输移特征分析

泥石流堆积及其对主河河床演变和输沙特征影响的研究已有不少成果问世,但基于实地观测数据的具体演化过程的分析研究还不多见,以2008年至2010年蒋家沟入汇段小江河床地形断面监测和采样分析为基础数据,结合泥石流活动的观测资料,对蒋家沟入汇后泥沙物质的堆积及其再起动输沙特征进行了分析。蒋家沟入汇的泥石流固体物质主要堆积于入汇口以下500 m（主河宽10倍以内）的范围内,堆积量的多少与原堆积物被小江冲刷输移的量有关。泥石流物质在被小江输移的过程中沿途落淤而堵塞河道,常常引起主河小江的改道。泥石流物质的堆积使小江在入汇处形成节点,尽管近年来入汇口附近小江河床总体表现为冲刷的趋势,但下游冲刷速度较上游快,导致下游河床比降增大而上游减小,入汇口的节点特征更为突出。     

中国走向强可持续性发展的战略选择

本文认为,近二十年来世界上许多国家发展的可持续性问题引起了很大争议,主要原因在于选择了弱可持续性和强可持续性两种不同范式作为测评标准.这两种范式争论的焦点在于判断自然资本与人造资本的替代性问题以及至关重要的自然资本度量问题的方式和标准.领先发展模式和U型发展模式证明,强可持续性是一国应该采用的标准,这两种模式也为中国的可持续发展之路提供了借鉴.文章提出,我国要实现强可持续发展目标,需要发展循环经济,提高生态效率,实行生态补偿机制,大力发展环保产业.     

Digital Technology in Teaching International Business

Abstract

As we enter the brave new world of interactive digital technology, teachers of International Business are being confronted with the problems and opportunities associated with integrating the new medium with a subject area that is inherently geographically dispersed. This analysis extends the traditional marketing tradeoffs between richness (depth of knowledge) and reach (geographic area coverage) to the emerging technology-mediated education industry, and then specifically evaluates their effect on the teaching of International Business. We believe that interactive learning, particularly as it applies to team building and problem solving in a multicultural environment, will prove valuable as the next generation of business leaders begins to emerge from academic institutions.     

The Urban Unbound: London's Politics and the 2012 Olympic Games

Global events such as London's 2012 Olympic Games raise questions about the ways in which embedded political arrangements take their shape from relationships that stretch across and beyond urban boundaries. In this article, the urban politics that we wish to capture is not one that is merely located in the city, but rather one that has to constantly take into account the mediated demands folded (as it were) into the urban arena. In the first part of the article, the corporate politics of an Olympic‐related urban regeneration are outlined and then considered, first as a staged setting for interaction, a kind of placeless political engagement, and then as a more embedded spatial politics that takes into account the leverage of networked groups acting within and beyond the city. Following that, we explore the politics of regeneration when campaign groups and alternative coalitions of interest raise their own political demands by drawing on references outside of their immediate urban area and attempt to steer political dialogue in ways that extend the reach of urban politics. The urban politics at stake in this context, we argue, appears to work more through topology than a series of mapped connections; through actors registering their presence in ways that often dissolve the tension between inside and outside rather than define it in terms of separate political spaces.     

三水源新安江模型在黄河三小区间的应用

三水源新安江模型在南方湿润地区精度较高,在北方半湿润半干旱地区的应用经验不多。应用三水源新安江模型对黄河三门峡~小浪底区间(以下简称三小区间)进行了产汇流模拟计算。经过对1980年以来的7次洪水进行产汇流模拟计算,小浪底站平均确定性系数0.85,可用于小浪底水库入库洪水预报。     

Modeling heterogeneous effective advertising stock using single-source data

This paper presents a nonlinear modeling of market response between advertising stock and direct utility with heterogeneous parameters using single-source data. We examine advertising threshold effects and measure the effective advertising stock at the individual consumer level. Two kinds of information, i.e., TV advertising exposure data and consumer’s purchase history data, are combined for the modeling. The former is used for constructing advertising stock over calendar time via heterogeneous carryover parameters and the latter is applied to the choice model. The Markov chain Monte Carlo (MCMC) method is applied to estimate these heterogeneous parameters. Compared to other possible nonlinear specifications, it is shown that the proposed threshold utility function model with discontinuity at the threshold performs better than other smooth market response models. The empirical results support the existence of an advertising threshold and suggest the pulsing or “on/off” policy for our datasets. In terms of the effective reach, implying the reach after suspending the ad exposure to investigate how it is damping out for a possible “on/off” advertising policy, the optimal “off” interval was measured to be quite short to support a high-frequency pulsing policy, because the carryover parameter as well as the difference of ad stock and threshold are not large enough for our datasets.