不同繁殖方式蓝莓苗木生长生理特性研究

为探寻蓝莓苗木最佳繁殖方式,对兔眼类蓝莓"灿烂"和高丛类蓝莓"莱克西"的组培与扦插2种不同繁殖方式苗木进行生长生理特性观测研究,结果表明:其净光合速率日变化分别在10:00时和14:00时呈现2个高峰曲线,12:00时出现峰谷。其中"灿烂"扦插苗的净光合速率最大,其次是"莱克西"扦插苗。扦插苗和组培苗的叶绿素a、叶绿素b、硝态氮含量、根系活力等均差异显著(p<0.05),硝态氮含量最大的是"莱克西"扦插苗,最小的是"莱克西"组培苗;根系活力大小顺序为"莱克西"组培苗>"莱克西"扦插苗>"灿烂"组培苗>"灿烂"扦插苗。对不同繁殖方式下蓝莓幼苗的净光合速率、胞间CO_2浓度、气孔导度、蒸腾速率、硝态氮含量、根系活力、叶绿素总量等7个指标进行主成分分析,其主成分值大小依次是"莱克西"组培苗>"莱克西"扦插苗>"灿烂"组培苗>"灿烂"扦插苗,反映出不同蓝莓种类及不同繁殖方式苗木生理特性指标的强弱差异。     

Towards the Spatial Patterns of Sectoral Adjustments to Trade Liberalisation: The Case of NAFTA in Mexico

ABSTRACT A recent string of “new economic geography” (NEG) models has set focus on the impacts of trade liberalisation on the intra‐national distribution of economic activity. What the existing contributions have in common is a basic two‐sector assumption (agriculture/manufacturing) and a resulting focus on the question of whether liberalisation leads to a greater concentration of aggregate manufacturing activity. Reconsidering these models from a multi‐sectoral perspective, the aim is to allow for sectoral differences in the spatial adjustments to liberalisation. This introduces a conceptual nexus between comparative advantage (CA)‐type sectoral recomposition effects of trade and NEG‐type spatial adjustments. In the analysis of Mexican manufacturing location 1993–2003, incipient empirical evidence is found in favour of the hypothesis that sectors characterised by a revealed comparative advantage and/or cross‐border intermediate supplies grow faster in regions with good foreign market access, whereas import competing ones gain in relative terms in regions with higher “natural protection” from poor market access. The relevancy of the proposed NEG/CA framework concerns both efficiency and equity objectives of trade adjustment policies, and opens a new perspective on the long‐run effects of trade on spatial inequality.     

In the gateway's shadow: Interactions between Singapore's Hinterlands

During the 1990s, Singapore, the Malaysian state of Johor and the Riau Islands in Indonesia marketed themselves as a single investment destination. Due to its capital, technology, and superior logistics, Singapore was the “gateway”; Johor and the Riau Islands were the hinterland—supplying land, labour, and resources. Since then, production networks between the three territories have deepened. Interactions with Singapore have also catalysed connections between Johor and the Riau Islands. To date, research has focussed on the city‐state as the gateway and/or linkages between it and one of the two hinterlands. This emphasis is inherent in the “Gateway City” framework, which focusses on the primary city at the expense of its hinterlands and also overlooks mediating influences such as borders and border regimes. This article proposes complementing the Gateway City with the Cross‐Border Region framework to gain stronger purchase on the unit of analysis and focusing on inter‐hinterland dynamics to gain a more complete picture of how gateway cities affect their surrounding areas. Through applying this expanded theoretical framework to study the interactions of Johor and the Riau Islands, this article seeks to shed light on an under‐theorised and under‐studied aspect of gateway cities.     

Independent and linked migrants: determinants of African American interstate migration

Through kinship and other links to destinations, many African American interstate migrants in the United States join other people in destination households. These “linked” migrants contrast to “independent migrants” who move as individuals or intact groups and set up their own households at the destination. Using U.S. Census Public Use Micro Sample data, this paper first shows that, in the 1985-90 period, about 45 percent of all Black interstate migrants were independent, compared to 38 percent who were linked to housing at the destination and 17 percent who moved into group quarters. Second, a multinomial logit model, incorporating individual and state-level variables, is specified that contrasts the determinants of independent and linked migration. Tests show that independent migration can be modeled with classic migration determinants, including individual educational and occupational resources, labor market conditions at the destination, and public goods at the destination including the level of welfare payments. Linked migration, on the other hand, is much less responsive to these factors, and not at all responsive to destination unemployment and welfare levels. Separate tests of male and female models suggest a great contrast between independent and linked migration for females. It is concluded that the understanding of Black migration must take into account a variety of factors beyond traditional labor market conditions, including links to the destination and individual housing circumstances.     

The Power of Governance in Financial Relationships: Governing Tensions in Exotic Infrastructure Territory

ABSTRACT The scope of financial products has recently extended to include investments in infrastructure assets that were previously community owned. While private investment in infrastructure is not new, the rise of institutional investors searching for infrastructure investments to match long‐term liabilities is a recent phenomenon. Most cannot hire the necessary expertise or take on the relatively large risks that accompany undertaking such endeavors in‐house, with many opting to place capital in specialised infrastructure funds. While there is a plethora of studies on various aspects of public and corporate governance, this paper concentrates on the governance of relationships between institutional investors and their infrastructure fund managers, contributing to the growing body of literature on financial geographies through a focus on the decision‐making of financial actors at the micro level, where the origins and destination of capital into geographies are determined. This private governance is defined as the “regulation” by private agents, insofar as they must anticipate and deal with potential or inherent conflicts of interest. Even as the “embedded” argument stresses the role of concrete personal relations and networks in generating trust, when interests need to be safeguarded in new and unfamiliar settings such as in infrastructure equity investing, the scope of private governance plays a central role in creating the financial relationship. This is supported through a discussion of four problems in private infrastructure governance, which are affected by but also have an impact upon the development of trust and long‐term relationships. Despite differing constraints and various degrees of negotiating leverage, innovative economic action is structured through anticipating and aligning diverging interests of (new) social relations.     

Nitrogen fertilization of warm‐season turfgrasses irrigated with saline water from varying irrigation systems. 1. Quality,spring green‐up and fall colour retention

A 3‐year study was conducted at New Mexico State University in Las Cruces, NM, to investigate the effects of different fertilization treatments on turf performance when water conservation strategies are applied. These strategies include the use of non‐potable saline irrigation water and the use of efficient subsurface irrigation systems. Two low water use warm‐season grasses, “Princess 77” bermudagrass (Cynodon dactylon L.) and “Sea Spray” seashore paspalum (Paspalum vaginatum O. Swartz), were irrigated with either potable [Electrical Conductivity (EC) = 0.6 dS/m] or saline (EC = 3.1 dS/m) water from either an overhead or a subsurface drip irrigation (SDI) system. Four different fertilizers, liquid slow release, granular slow release, granular urea and liquid urea, were applied at two rates: 10 and 20 g N m^?2 year^?1 for “Sea Spray” and 20 and 30 g N m^?2 year^?1 for “Princess 77.” Spring green‐up, summer quality and fall colour retention were determined using digital image analysis, visual quality ratings and normalized difference vegetation index. Generally, subsurface drip‐irrigated grasses were slower to green‐up than overhead irrigated ones. “Sea Spray” irrigated from the SDI system took 18, 28 and 15 days longer to reach 80% green cover in 2010, 2011 and 2012, respectively, than their sprinkler‐irrigated counterparts. The combination of “Princess 77” and overhead irrigation reached 80% green cover 35 (in 2010), 34 (in 2011) and 12 (in 2012) days faster than SDI‐irrigated “Princess 77.” Fertilization rate and type had no effect on summer turfgrass quality of “Princess 77” irrigated from a sprinkler system throughout the research period reaching ratings of greater than 7 during all 3 years. Similar results were observed for “Princess 77” irrigated from a SDI system during 2010 and 2011. Summer quality of sprinkler‐irrigated “Sea Spray” was negatively affected by liquid fertilization. During two of three summers, visual quality of plots fertilized with either liquid slow release or liquid urea was lower than “Sea Spray” fertilized with granular fertilizer. Further research is needed to investigate the effect of fertilization on bermudagrass and seashore paspalum over a wider nitrogen range including both granular and foliar products.     

Polish Labour Migration to the UK: Data Discrepancies,Migrant Distributions,and Indicators of Entrepreneurial Activity

This paper contributes to a growing body of work on labour market migration to the UK from the new Member States (NMS) of the European Union, particularly the migration of Polish nationals to the UK, drawing attention to the weaknesses of existing data sets which attempt to quantify these migration flows and in particular to map the geographical distribution of migrants. The analysis of Worker Registration Scheme (WRS) and National Insurance Number (NINo) allocation data demonstrates that NMS migration has focused on urban and rural locales rather than having a predominantly rural or “peripheral” area bias. The paper also argues that the discrepancies between WRS and NINo data potentially reveal a “hidden” geography of self‐employment and entrepreneurial activity among NMS migrants which merits further investigation.     

Critical Transport Infrastructure in Urban Areas: Impacts of Traffic Incidents Assessed Using Accessibility‐Based Network Vulnerability Analysis

Incidents (vehicle breakdowns, crashes, roadworks, lane blockages, severe weather, etc.) are believed responsible for about 50 percent of traffic congestion in Australia's major cities, which is a similar situation to that found in cities in many other parts of the developed world. Incident‐based congestion is particularly disruptive because of its random occurrence in space and time, which maximises the operational impacts of the congestion on social and economic activities. This paper discusses a method for assessing critical locations—congestion “hot spots”—in urban road networks, and the development and application of diagnostic tools that will allow urban road system managers to anticipate potential vulnerabilities to incident‐related congestion and take proactive action to avoid congestion rather than react to it. The expected outcomes are then reduced congestion, delays, and pollution; significantly improved performance from the existing urban road system; and reduced pressure to build more roads. The method involves modelling of travel demand, network topology, capacity and road geometry, the identification and assessment of impacts of traffic incidents at specific locations in a road network, and the use of accessibility impact analysis to assess system‐wide effects. Accessibility impact analysis is undertaken using an accessibility framework, which can account for time of day, transport mode and destination choices by individuals, and level of traffic congestion among other factors. A case‐study application to a specific (potential) incident in a real‐world network indicates that the proposed method is feasible and demonstrates its power in identifying not just total impacts but the distribution of those impacts across a region or community. While current approaches to urban road network planning and management tend to be reactive—finding cures for problems as they arise or addressing locations of recurrent congestion or bad incident record—the vulnerability analysis method described in the paper should lend itself to a proactive approach that can anticipate structural weaknesses and vulnerabilities and help to avoid or at least temper potential adverse effects, rather than to react to them afterwards.     

Genetic analysis of yield and fruit traits in cantaloupe cultivars

The purpose of this research was to evaluate the combining ability of six local Iranian and one imported cantaloupe cultivar. Heritability of traits was estimated using a half‐diallel mating design. Seven parents and their crosses were evaluated in 2013 and 2014. The greatest general combining ability (GCA) for yield and fruit number was for “Rish‐baba” (0.53 kg/plant and 0.3, respectively). The cultivar “Ananasi” had the highest GCA for fruit weight and soluble solids content (SSC) (0.088 kg and 1.4, respectively). “Ananasi” presented the highest GCA values for fruit firmness, chlorophyll a and b and carotenoid content, as well as the highest total chlorophyll content. The cross Garmak × Rish‐baba showed the highest specific combining ability (SCA) for yield with heterosis value of 99%. High heritability estimates for SSC (0.52), flesh thickness (0.61) and concentration of chlorophyll a (0.7) were obtained. Although there were significant SCAs for yield, the parents are suggested to be improved prior to hybrid development. The parent “Ananasi” appears to be a suitable donor in breeding programmes.     

Marriage Markets and the Intermetropolitan Distribution of Skilled Couples

Costa and Kahn hypothesize that the growing concentration of skilled couples in large cities is due to their migration to large cities to solve their dual‐employment problem. However, there is only limited empirical evidence in support of this hypothesis. This research tests an alternative hypothesis: The intermetropolitan distribution of skilled couples is largely the result of marriages among skilled singles in large cities. The relative merits of both the “co‐location” and “marriage market” hypotheses are evaluated by comparing the effects of migration and marriage on the intermetropolitan distribution of dual‐degree couples using data from the 2008 American Community Survey. Migration is found to have little effect on the distribution of dual‐degree couples. Rather, the concentration of dual‐degree couples is strongly related to the high rate of marriages among single college graduates in the same cities.     

New Insights into Senior Travel Behavior: The Canadian Experience

Societies in many developed nations around the world are aging. Over the past decade, a growing body of research has emerged internationally in an effort to anticipate and prepare for the transport challenges posed by this unprecedented demographic change. This paper contributes to this line of research by offering new insights into senior travel behavior focusing on the recent Canadian experience. Using weekday data from the 1992 and 2005 General Social Surveys on time use, changes in the number of trips, the duration of trips, trip mode, and trip timing are evaluated for urban seniors. In contrast to the experiences of many other developed nations, analysis of the first three indicators of behavioral change refutes the notion that “automobility” has increased in Canada over the 13‐year period. While this finding is encouraging, it is tempered by the fact that Canadian seniors who choose to travel by car are doing so increasingly during the morning and evening peak periods. The results from a peak versus non‐peak departure‐time model that pools data from both years offer important insights into factors driving this change. For instance, the results suggest that the propensity to start a trip during rush hour has increased over time for non‐work trip purposes.     

Generation and analysis of expressed sequence tag sequences from a soft‐seeded pomegranate cDNA library

The cultivation of soft‐seeded pomegranate is an important direction in pomegranate breeding. To comprehensively understand the molecular mechanisms involved in the formation of soft‐seeded pomegranate (Punica granatum. var. Hongmanaozi), we established an expressed sequence tag (EST) resource. Two thousand valid sequences were generated, from which 907 unigenes were obtained after initial assembly using the clustalx program. Among these unigenes, 51 showed no similarity to any protein in the public databases, 433 matched with proteins of unknown function, and 423 matched with proteins of known or putative functions. The 423 unigenes were further classified into 13 categories. Among these categories, protein synthesis, cell structure, protein destination and storage, secondary metabolism, signal transduction and transporters accounted for 8%, 8%, 4%, 7%, 6% and 17%, respectively. We also successfully developed 10 highly polymorphic expressed sequence tag‐simple sequence repeat (EST‐SSR) markers for pomegranate. The results provide a new tool for future activities in pomegranate breeding.     

Urban Form and Household Activity‐Travel Behavior

ABSTRACT Cities and metropolitan regions face several challenges including urban sprawl, auto dependence and congestion, and related environmental and human health effects. Examining the spatial characteristics of daily household activity‐travel behavior holds important implications for understanding and addressing urban transportation issues. Research of this sort can inform development of urban land use policy that encourages the use of local opportunities, potentially leading to reduced motorized travel. This article examines the potential household activity‐travel response to a planned metropolitan polycentric hierarchy of activity centers. Behavioral observations have been drawn from an activity‐travel survey conducted in the Portland, Oregon, metropolitan area during the mid‐1990s. Evidence presented from exploratory analysis indicates an urban/suburban differential, with less daily travel and smaller activity spaces for urban households. Investigation of the travel reduction potential of the proposed land‐use strategy suggests that location effects could be offset by adjustments to household sociodemographic and mobility characteristics.     

Solving the Problems of Economic Development Incentives

ABSTRACT This paper reviews the research literature relevant to economic development incentives provided by state and local governments, and recommends reforms in these incentives. I argue that the main problem with current incentive policies is that state and local governments often provide incentives that are not in the best interest of that state or local area, for example that are excessively costly per job created, or that provide jobs that do not improve the job opportunities of local residents. I suggest that reforms should be “bottom‐up” rather than “top‐down.” Regulation of incentives by the federal government may prevent both desirable and undesirable incentives. “Bottom‐up” reforms would include more information on incentive offers, a budget constraint on the volume of incentives, stronger standards for job quality and job accessibility for the local unemployed, and better benefit‐cost analyses of incentives.     

Nothing is in the Air

It has often been argued that “there is something in the air” which makes firms in high‐density environments—such as cities or clusters—more innovative. The co‐location of firms facilitates the emergence of serendipity and casual encounters which promote innovation in firms. We assess this hypothesis using data from a survey of Norwegian firms engaged in innovation partnerships. The results indicate that there may be “much less in the air” than is generally assumed in the literature. The relationships conducive to innovation by Norwegian firms emerged as a consequence of purpose‐built searches and had little to do with chance, serendipity, or “being there.”     

基于AHP/BCG的农业气象服务效益评估方法研究

为了科学、准确地对农业气象服务效益进行评估和分析,结合威武市当地农业气象服务的特点,利用AHP（层次分析法）与BCG（波士顿矩阵）相结合的方法,将复杂的效益评估系统数学化、层次化、系统化,构建适合当地特色的新型农业气象服务效益评估模型,结合2015年武威市农业气象服务满意度调查问卷进行效益评估。结果表明,“气象部门对当地农业气象需求的了解程度与带来的社会和经济效益”、“预报要素准确率”、“气象服务产品特性”、“农业气象产品内容丰富性”等4类指标属于核心类项目,成为农气象服务中产生良好社会和经济效益的主要指标项目,“用户未来打算”属于发展型项目,具有良好的发展潜力。此次评估结果,能够使气象部门合理确定服务产品重点、改进服务内容,积极拓宽服务信息发布渠道,有效分配农业气象服务资源,对提高农业气象防灾减灾水平有着重要意义。     

Increasing pre‐acclimation temperature reduces the freezing tolerance of winter‐type faba bean (Vicia faba L.)

Autumn‐sown winter‐type faba bean (Vicia faba L.) has been shown to have a yield advantage over spring sowing. Still, adoption of this overwintered pulse crop remains limited in temperate locations, due to inadequate winter hardiness. This research sought to understand how the prevailing temperature during emergence and seedling development, that is pre‐acclimation, influences freezing tolerance. Seedlings grown under a controlled “warm” 17/12°C (day/night) pre‐acclimation environment were initially less freezing tolerant than those grown under a “cold” 12/5°C temperature treatment. Stem and particularly root tissues were primarily responsible for slower cold acclimation, and there was a genotype specific response of above‐ground tissues to pre‐acclimation treatment. Both above and below‐ground tissues should be tested across a range of pre‐acclimation temperatures when screening faba bean germplasm for freezing tolerance.     

Location Decision Making of “Creative” Industries: The Media and Computer Game Sectors in Dublin,Ireland

There has been significant research undertaken examining the “creative class” thesis within the context of the locational preferences of creative workers. However, relatively little attention has been given to the locational preferences of creative companies within the same context. This paper reports on research conducted to qualitatively analyse the location decision making of companies in two creative sectors: media and computer games. We address the role of the so‐called “hard” and “soft” factors in company location decision making within the context of the creative class thesis, which suggests that company location is primarily determined by “soft” factors rather than “hard” factors. The study focuses upon “core” creative industries in the media and computer game sectors and utilises interview data with company managers and key elite actors in the sector to investigate the foregoing questions. The results show that “hard” factors are of primary importance for the location decision making in the sectors analysed, but that “soft” factors play quite an important role when “hard” factors are satisfactory in more than one competing city‐region.     

Public Education Financing Trends and the Gray Peril Hypothesis

The effects of migrating seniors on the provision of local public services in rural communities is growing in importance because of the large number of retiring baby boomers and the increasing rate at which these retirees are locating outside traditional retirement destinations. Some communities are optimistic about attracting and retaining retirees as an economic development strategy, but others are concerned that inmigrating seniors may be reluctant to support local public services, such as education, bringing with them “Gray Peril.” This article attempts to clarify questions regarding the Gray Peril hypothesis and local ability and willingness to fund education in Tennessee, an increasingly popular retirement destination. To this end, county per pupil education expenditure growth is explained by growth trends in local property tax assessment and sales tax revenue, and migration patterns of the retirement‐aged population from 1962 to 2002.