Order statistics from trivariate normal and -distributions in terms of generalized skew-normal and skew- distributions

We consider here a generalization of the skew-normal distribution, GSN(λ₁,λ₂,ρ), defined through a standard bivariate normal distribution with correlation ρ, which is a special case of the unified multivariate skew-normal distribution studied recently by Arellano-Valle and Azzalini [2006. On the unification of families of skew-normal distributions. Scand. J. Statist. 33, 561–574]. We then present some simple and useful properties of this distribution and also derive its moment generating function in an explicit form. Next, we show that distributions of order statistics from the trivariate normal distribution are mixtures of these generalized skew-normal distributions; thence, using the established properties of the generalized skew-normal distribution, we derive the moment generating functions of order statistics, and also present expressions for means and variances of these order statistics.Next, we introduce a generalized skew-t_ν distribution, which is a special case of the unified multivariate skew-elliptical distribution presented by Arellano-Valle and Azzalini [2006. On the unification of families of skew-normal distributions. Scand. J. Statist. 33, 561–574] and is in fact a three-parameter generalization of Azzalini and Capitanio's [2003. Distributions generated by perturbation of symmetry with emphasis on a multivariate skew t distribution. J. Roy. Statist. Soc. Ser. B 65, 367–389] univariate skew-t_ν form. We then use the relationship between the generalized skew-normal and skew-t_ν distributions to discuss some properties of generalized skew-t_ν as well as distributions of order statistics from bivariate and trivariate t_ν distributions. We show that these distributions of order statistics are indeed mixtures of generalized skew-t_ν distributions, and then use this property to derive explicit expressions for means and variances of these order statistics.     

基于“3R＆I”原则的循环经济模式研究

我国当前经济高速增长的要求与有限资源和环境支持能力之间存在严重矛盾。实施循环经济是贯彻落实我国节能减排政策的有效途径，如何发展循环经济是我们面临的重大课题。目前循环经济的实施主要是依据“3R”原则，而这些原则有明显的不足之处。针对“3R”原则的局限性，提出基于创新的循环经济“3R＆I”原则。创新是实现“减量化”、“再利用”、“资源化”的前提，也是实现经济持续循环的保证。循环经济本质上是一种创新经济。     

基于Solid works蜗轮蜗杆三维建模的研究

在Solid works环境下进行了蜗轮蜗杆三维设计研究,这对类似复杂曲面的零件设计具有实际意义。     

The social security number: A small device underpinning big systems

The possession and use of a personal social security number helps to structure people's daily lives. However, despite its fundamental normative importance, the social security number remains a little‐known entity. Increasingly universal and yet diverse in form, it is a legal and technical norm which is as much a mechanism for surveillance and monitoring as it is a necessary instrument for giving effect to social rights. Analysis of this constituent element of social security systems permits as assessment of some of the technical difficulties presented by the ever‐increasing movement of people and data. Overcoming these technical difficulties should permit to envisage a first technical step towards realizing a universal and global social security system.     

Do people think about absolute or relative price differences when choosing between substitute goods?

The article presents experimental evidence that shows that people often consider relative price differences in addition to absolute differences when choosing between substitute goods. Because the choice between substitute goods is a very common one, this is an important finding. The experiment uses scenarios in various consumption categories: hotel rooms, flights, and books. Subjects were either students or participants in an economics conference. The data allow to reject the hypothesis that people think only about relative price differences in favor of the hypothesis that people think about both relative and absolute price differences. Whether the price given to the subjects is that of the high-quality good or of the low-quality good makes a large difference, a result that is related to the endowment effect and the status quo bias. Implications of the results for business strategy and other areas are also discussed.     

Family farmers and major retail chains in the Brazilian organic sector: Assessing new development pathways. A case study in a peri-urban district of São Paulo

The expansion of the organic sector in Brazil is seen as a leverage for the social emancipation of the small family farmers. Next to the traditional alternatives circuits of organic food and farming, new powerful capitalistic actors, such as supermarket chains, are rapidly entering the Brazilian organic arena. Can family farming benefit from the development of these “conventional” commercialisation circuits in the organic sector? Research undertaken in 2007, in a green belt rural community of São Paulo, shows how family farmers may have benefited from the implication of large retail chains in the organic sector and how an economically and ecologically outstanding agriculture may arise from these circumstances. However, we highlight the crucial role played by social regulation: only strong solidarity between farmers and the implication of technicians, militants and researchers in the process made it possible to counter the negative effects of the liberal logic governing the development of organic farming via the major retailers. Still, as tougher competition is expected on the regional organic market, the development of short supply chains involving “committed” consumers and the broader integration of the local farmers in networks of organic militancy appear crucial. It would guarantee a continuous enhancement of the local human and social capital, reinforce an emerging process of internal conversion and allow for a stronger social regulation of the future local development pattern.     

东西相遇：中德双校园学习差异性比较分析——基于Z大学中德合作2＋3项目学生的访谈

在对Z大学中德合作2＋3项目留德学生访谈的基础上，以差异性分析为视角，从教学组织、专业学习和校园生活三个纬度，分析了项目学生对两校园学习的差异性体验，并从文化价值、教育体制、教育投入方面探究其原因，提出了强化国际合作、提升师资能力水平、加大工程实训领域投入等对策。     

论3G时代高校图书馆的发展

3G时代图书馆工作面临新的考验。为了应对这一革命性的冲击，高校图书馆要做好数字化的核心准备工作，逐步建立并完善例如“手机图书馆”的建设。一方面可以提高数字化图书的普及与使用率，另一方面也可以在演进的过程中确实保护高校的既得利益。     

Impact of metabolic status on the association of serum vitamin D with hypogonadism and lower urinary tract symptoms/benign prostatic hyperplasia

Objective: The objective of this study is to investigate the impact of metabolic status on associations of serum vitamin D with hypogonadism and lower urinary tract symptoms (LUTS)/benign prostatic hyperplasia (BPH).

Patients and methods: A total of 612 men underwent physical examination, biochemical/hormonal blood testing, and transrectal prostate ultrasound. Moreover, the subjects filled out standard questionnaires for identification and grading of LUTS and hypogonadism symptoms. Parameters were statistically compared with independent t-tests and correlation analyses.

Results: Vitamin D levels positively correlated with total testosterone (TT) but not with prostate volume or International Prostate Symptom Score (IPSS). Patients with metabolic syndrome had significantly lower vitamin D levels, which were not correlated with TT, prostate volume, or IPSS. However, vitamin D was positively correlated with TT, and negatively correlated with prostate volume and quality-of-life IPSS in subjects without metabolic syndrome.

Conclusion: The clinical usefulness of vitamin D for treatment of hypogonadism or LUTS/BPH varies according to metabolic status.     

Consumer bankruptcy and default: The role of individual social capital

In this paper, we empirically assess the role of individual social capital on personal bankruptcy and default outcomes in the consumer credit market. After controlling for a borrower’s risk score, debt, income, wealth, and legal and economic environments, we find that default/bankruptcy risk rises and then falls over the lifecycle, while a borrower who owns a home or is married has a lower risk of default/bankruptcy. Moreover, a borrower who migrates 190 miles from his “state of birth” is 17% more likely to default and 15% more likely to file for bankruptcy, while a borrower who continues to live in his state of birth is 14% and 10% less likely to default and file for bankruptcy, respectively. A borrower who moves to a rural area is 9% and 7% less likely to default and declare bankruptcy, respectively. We also find that measures of social networks, norms, and cooperation and trust (i.e., aggregate social capital) are inversely related to consumer bankruptcy.