信任:构建和谐民族关系的社会基础

信任是促进人际关系融洽和社会秩序良性循环的重要前提,是促进民族关系和谐的社会基础。中国与世界民族关系的发展变化证明,信任对于促进民族关系健康发展具有重要作用。我国当今各民族基本上形成一种信任关系,但影响民族间不信任的因素仍然存在。要在各民族中形成一种信任关系的互动,必须坚持在各民族平等的前提下,以科学发展观为指导促进民族地区经济发展和社会繁荣; 同时需要各民族在沟通中加强相互理解、尊重与宽容,在相互认同的基础上以诚相待、彼此取信。     

越南的下高棉民族分离主义问题

下高棉人是今越南九龙江平原地区(历史上为“下柬埔寨”地区)的土著。下高棉人与越南主体民族越人(京人)之间在历史上形成的民族隔阂及现实矛盾,在世界民族分离主义浪潮的影响和外部敌对势力的煽动下,演变成下高棉人要求成立独立的“下高棉国家”的民族分离主义运动,对越南的社会、政治及对外关系产生了严重的影响。     

Franchise Contracting: The Effects of The Entrepreneur's Timing Option and Debt Financing

We solve a sequential‐moves game that involves three players: the franchisor, the entrepreneur, and the banks. The franchisor chooses the contract terms (a one‐time franchise fee and a royalty rate for on‐going payments). The entrepreneur dynamically decides when to sign this contract, open a store, and apply for debt financing to cover the initial investment. In response to the entrepreneur's application, banks competitively determine loan rates. We find that the franchisor should use royalty cash flows and not the franchise fee to extract value from the entrepreneur. This is a new explanation of empirical evidence that franchise contracts favor royalties over franchise fees. To account for the possibility of the entrepreneur's bankruptcy and bankruptcy costs, the franchisor should decrease the royalty rate. However, despite a lower rate, the threshold for the entrepreneur to open the store is higher in the model with financing than in the model without financing. This threshold is much higher than it would have been for the integrated system, which in turn is higher than the static break‐even‐NPV threshold. If a franchisor ignores financing considerations, she will suffer from having to wait longer for the store opening and from a higher bankruptcy probability. We predict that the franchisor is the main beneficiary of the entrepreneur's greater initial wealth and that the franchisor will benefit more if she assumes a greater share of the store's operating costs.     

Comparison of disease prevalence in two populations under double-sampling scheme with two fallible classifiers

A disease prevalence can be estimated by classifying subjects according to whether they have the disease. When gold-standard tests are too expensive to be applied to all subjects, partially validated data can be obtained by double-sampling in which all individuals are classified by a fallible classifier, and some of individuals are validated by the gold-standard classifier. However, it could happen in practice that such infallible classifier does not available. In this article, we consider two models in which both classifiers are fallible and propose four asymptotic test procedures for comparing disease prevalence in two groups. Corresponding sample size formulae and validated ratio given the total sample sizes are also derived and evaluated. Simulation results show that (i) Score test performs well and the corresponding sample size formula is also accurate in terms of the empirical power and size in two models; (ii) the Wald test based on the variance estimator with parameters estimated under the null hypothesis outperforms the others even under small sample sizes in Model II, and the sample size estimated by this test is also accurate; (iii) the estimated validated ratios based on all tests are accurate. The malarial data are used to illustrate the proposed methodologies.     

Aggregating Smallholder Farmers in Emerging Economies

The agricultural sector plays an important role in emerging economies even though most farmers are trapped in the poverty cycle owing to their smallholdings. Aggregating farmers through formal or informal cooperatives (coops) can enable them to: (i) reduce production cost; (ii) increase/stabilize process yield; (iii) increase brand awareness; (iv) eliminate unnecessary intermediaries; and (v) eliminate price uncertainty. To examine whether these effects will benefit the members of such aggregation when they compete with other individual farmers, we present separate models to capture the essence of these five effects. For each effect, we find that it is beneficial for a farmer to be part of the aggregation only when the size of the aggregation is below a certain threshold. Also, while certain effects are beneficial to the market as a whole, other effects are hurtful due to higher market price and/or lower production quantity.     

西藏山南地区民居院门文化刍议

西藏的建筑艺术是祖国建筑艺术宝库里的珍品,而西藏山南地区的民居院门艺术更是西藏建筑艺术的精品,堪称藏区一绝。笔者经调查研究西藏山南地区民居院门的结构、功能、理念、装饰和民俗,发现其承载着丰富多彩的民族文化内涵。     

城乡因素在老年人抑郁症状影响模型中的调节效应

抑郁症状是衡量老年人心理健康水平的有效指标。本研究采用2006年中国城乡老年人生活状况追踪调查10%数据,运用探索性因素分析、多元线性回归和结构方程模型等方法考察中国老年人的总体抑郁水平,比较抑郁水平的城乡及年龄差异,并对老年人抑郁症状及影响因素进行探索。结果显示,我国老年人抑郁症状较轻,心理健康处于良好水平。农村老年人抑郁症状较城镇老年人明显。健康水平、经济状况、社会支持可有效地预测老年人的抑郁症状。城乡在影响因素模型中起调节效应,健康水平和经济状况对老年人抑郁水平的影响作用受城乡因素的影响,对于农村老年人,经济状况的影响作用大于健康水平;在城镇老年人中表现出完全相反的模式。对于不同的老年人群,应采取有针对性的政策和措施,方能有效减缓老年人抑郁症状,促进心理健康。     

Approximation and Exact Algorithms for Constructing Minimum Ultrametric Trees from Distance Matrices

An edge-weighted tree is called ultrametric if the distances from the root to all the leaves in the tree are equal. For an n by n distance matrix M, the minimum ultrametric tree for M is an ultrametric tree T = (V, E, w) with leaf set {1,..., n} such that d_T(i, j) M[i, j] for all i, j and is minimum, where d_T(i, j) is the distance between i and j on T. Constructing minimum ultrametric trees from distance matrices is an important problem in computational biology. In this paper, we examine its computational complexity and approximability. When the distances satisfy the triangle inequality, we show that the minimum ultrametric tree problem can be approximated in polynomial time with error ratio 1.5(1 + log n), where n is the number of species. We also develop an efficient branch-and-bound algorithm for constructing the minimum ultrametric tree for both metric and non-metric inputs. The experimental results show that it can find an optimal solution for 25 species within reasonable time, while, to the best of our knowledge, there is no report of algorithms solving the problem even for 12 species.