南方丘陵区新增耕地质量空间特征研究*——以江西省宜春市为例

［目的］粮食安全的根本是在耕地，关键在于耕地质量。目前新增耕地主要源于土地开发项目、城乡建设用地增减挂钩土地复垦项目等，这些新增耕地需要对其开展耕地质量等别评定工作，了解新增耕地的质量状况，分析其空间特征，这对落实国家耕地保护制度、开展农村土地整治工作等具有重要作用。［方法］文章以南方典型丘陵区域——江西省宜春市作为研究区域，在新增耕地质量评价的基础上，运用地统计学、景观生态学、Arcgis空间分析技术和典型相关分析方法，研究宜春市新增耕地质量的空间特征，掌握耕地质量等别的分布规律，了解耕地质量的影响因素，为制定合理的耕地资源利用与保护政策提供依据。［结果］（1）Moran′s I值结果表明宜春市2014年新增耕地利用质量在空间分布上的空间自相关性最强，而耕地自然质量空间自相关性最弱。（2）景观破碎度指数结果表明优、高等别的新增耕地质量破碎度大于中、低等别的； 多样性指数结果表明新增耕地质量多样性指数比较大； 优势度指数结果表明新增耕地质量等别优势度指数比较小，与多样性指数结果相呼应； 均匀度指数结果表明，新增耕地质量等别均匀度指数相差不大，新增耕地质量等别比较均匀。（3）质心结果表明2013—2014年间宜春市新增耕地质量的格局整体上是向西南方向变化。［结论］宜春市新增耕地质量不高； 新增耕地的利用水平差异性较小，自然本底状况差异较大； 新增耕地质量等别类型多，各质量等别类型耕地均有增加，耕地质量参差不齐，较高等地的新增耕地相对低等地而言更破碎化； 新增耕地的开发格局向着西南方向移动； 该研究为南方丘陵区的新增耕地保护提供了一定的参考依据。     

Evaluating museum visitor experiences based on user-generated travel photos

ABSTRACT

This research introduces online travel photos published on social media platforms as a complementary data resource to examine the behavior and experience of museum visitors. The practical value of online travel photos is demonstrated through a case study of popular Hong Kong museums, particularly by using the photo content and metadata available from the Flickr platform. The proposed approach is a generic method for understanding museum visitor behavior and preferences, and supports museum practitioners in developing improved products for visitors. The case study findings are particularly beneficial for tourism managers, especially those in Hong Kong, in promoting and attracting tourists to visit local museums.     

Childhood adversity and the propensity for entrepreneurship: A quasi-experimental study of the Great Chinese Famine

Studies on the determinants of entrepreneurship emphasize that challenged adults tend to become entrepreneurs. However, research has not addressed the childhood origins surrounding the propensity for entrepreneurship. This article links childhood adversity to the propensity of individuals to become migrant entrepreneurs later in life. We test hypotheses derived from this theory in the context of whether, and when, children who survived the Great Chinese Famine of 1959–1961 became migrant entrepreneurs. Results strongly indicate that those who survived greater hardship during the Famine are more likely to become entrepreneurs, especially when they were younger during the famine years. We also find that being younger at the time of migration increased the likelihood of becoming entrepreneurs in their new locale. Overall, this study casts light on why, how and when childhood adversity shapes the propensity for entrepreneurship.     

城市道路桥梁工程施工技术要点

整个道路桥梁工程施工质量从很大程度上受到施工技术合理性影响.城市道路桥梁关系着国民日常出行便捷与安全,为此需要做好施工技术合理选择,确保落实各项技术,保证施工项目质量,加强成本控制.通过明确道路桥梁施工技术要点有助于落实施工技术方案,有助于工程质量优化,促进企业未来发展.为此,应当在明确道路桥梁工程施工要点基础上,加强各项技术应用,并且加强施工质量管控,建设优质项目.     

EMPIRICAL PERFORMANCE OF GARCH MODELS WITH HEAVY‐TAILED INNOVATIONS

We introduce a new type of heavy‐tailed distribution, the normal reciprocal inverse Gaussian distribution (NRIG), to the GARCH and Glosten‐Jagannathan‐Runkle (1993) GARCH models, and compare its empirical performance with two other popular types of heavy‐tailed distribution, the Student's t distribution and the normal inverse Gaussian distribution (NIG), using a variety of asset return series. Our results illustrate that there is no overwhelmingly dominant distribution in fitting the data under the GARCH framework, although the NRIG distribution performs slightly better than the other two types of distribution. For market indexes series, it is important to introduce both GJR‐terms and the NRIG distribution to improve the models’ performance, but it is ambiguous for individual stock prices series. Our results also show the GJR‐GARCH NRIG model has practical advantages in quantitative risk management. Finally, the convergence of numerical solutions in maximum‐likelihood estimation of GARCH and GJR‐GARCH models with the three types of heavy‐tailed distribution is investigated.     

Social media affordances in entry‐level employees’ socialization: employee agency in the management of their professional impressions and vulnerability during early stages of socialization

This study examined how entry‐level employees interacted with social media during three stages of organizational socialization. They navigated between four different media affordances (persistence, editability, visibility, and association) while experiencing them as both enabling and constraining in different socialization stages. Qualitative interview data analysis revealed during anticipatory socialization, job applicants realized visibility and persistence in relation to institutional and individualized socialization. During encounter, new employees managed personal and professional life boundaries carefully against the association and visibility affordances. Although some participants used both public and enterprise social media for obtaining job‐related information and understanding coworkers and company culture, during metamorphosis, most interviewees adopted passive information seeking strategies and experienced a paradoxical tension between the enabling and constraining affordances of social media. Findings are discussed with regards to employees’ exertion of agency in managing their professional impressions and coping with high levels of uncertainty and vulnerability during early stages of socialization.     

A REVIEW OF THE EMPIRICAL LITERATURE ON FARMER COOPERATIVES: PERFORMANCE,OWNERSHIP AND GOVERNANCE,FINANCE, AND MEMBER ATTITUDE

The empirical literature on farmer cooperatives is now fast emerging and developing in the areas of performance, ownership and governance, finance, and member attitude. We discuss 56 peer‐reviewed publications to illustrate the main findings and conclusions while outlining challenges and opportunities for future research. Generally, cooperative membership is found to positively impact price, yield, input adoption, income, and other indicators of member performance, yet there is growing evidence of an uneven distribution of benefits for small and large producers. In terms of structure, evidence of a causal relationship of ownership and governance to performance has been elusive, yet there are now many findings of inherent equity and long‐term debt constraints, often in the context of consolidation to drive scale and scope economies. Further inefficiency is observed to be driven by increased heterogeneity in member attitudes and objectives, in particular in terms of commitment and participation. Thus, overall, empirical work portrays farmer cooperatives as flawed and complex business organizations which nonetheless have a strong positive impact on its members. While applied research may progress in various directions, a general improvement in empirical methodologies is needed to allow robust analysis of mixed objectives in dynamic environments.     

工业体系和民营企业兴起——基于252家中国最大民营制造业企业的经验研究

主流经济学家把改革开放后民营企业的大规模兴起，主要归因为市场经济条件下发挥企业家精神和遵循比较优势的必然结果。但是这无法解释为什么民营企业在兴起之初就广泛和快速地进入到各个工业，尤其是技术和资本密集型工业。基于中国工业史和252家中国最大民营制造业企业创业发展史的历史证据，文章找回"工业体系"这一被主流所忽略的重大历史现象和学术概念，从而首次提出一种理解中国民营企业发展独特性的结构性解释。文章发现：从计划经济时期继承而来的门类齐全和独立完整的工业体系，是解释民营企业创业和发展独特性的关键变量；已有的由国有企业和科研院所组成的工业体系，从市场机会、技术能力和组织资源等方面塑造了民营企业的创业选择和发展路径。所以，中国民营企业的快速发展不是仅凭自由市场就会自动出现的普遍现象，而是在市场条件下充分利用工业体系提供的技术和市场条件才得以出现的特殊现象。     

Estimating yield curves of the U.S. Treasury securities: An interpolation approach

Following the approach of interpolation, this paper proposes the multiple exponential decay model to fit yield curves for both the U.S. TIPS market and the conventional Treasury security market. Several estimation methods, including the unconstrained/constrained nonlinear minimization, quadratic programming, and the iterative linear least squares, are applied to estimate the unknown parameters according to different curve‐fitting purposes. Comparisons between the proposed model and the alternatives show that the multiple exponential decay successfully (1) adapts to a variety of shapes associated with yield curves, (2) (partially) keeps in line with the economic interpretations of Nelson–Siegel summarized by Diebold and Li ( 2006 ), and (3) dominates the competing models in curve‐fitting performance measured by mean fitted‐price errors over the sample period. In addition, the exact specification of a nonparametric interpolation model is pinned down by applying three statistical tools, which enable us to jointly take into account validity, optimality, and parsimoniousness of the proposed model.