聚乙二醇-硫酸铵双水相体系萃取分离食用色素的研究

研究了硫酸铵-聚乙二醇（PEG）双水相体系中,PEG浓度、（NH4）2SO4用量、Trition X-100用量、溶液酸度等因素对常见食用色素叶绿素铜钠盐（SCC）萃取率的影响。研究表明,在50mL的总体积中,聚乙二醇的浓度为30％,10％的SCC溶液的体积为1mL,（NH4）2SO4用量为10．0g,表面活性剂Trition X-100的用量为1．0mL,在中性或微碱性条件下,叶绿素铜钠盐的萃取率达97．98％。叶绿素铜钠盐最大吸收峰位于632nm,实验测定其溶液体积在0—1．2mL范围内符合比耳定律,标准工作曲线为Y=1．0117x＋0．0055,R=0．9999。在实验条件下,金属离子Zn^2＋、Mn^2＋、Mg^2＋、Fe^2＋、Ni^2＋、Cu^2＋对SCC的萃取均不干扰。     

模态系统T的Herbrand定理

模态Herbrand定理研究是模态逻辑领域的重要开放问题.不含Barcan公式的模态系统T的Herbrand定理的获得必须完成两个方向的证明工作:首先是证明相对简单的从右到左方向;而对于相对复杂的从左到右方向,则可以通过在加标公式表列系统K的基础上增加特殊规则获得加标公式表列系统T,证明T的可靠性和完全性,并在此基础上完成从左到右方向的证明.同样的方法还可以用来证明模态系统D、K4、s4的Herbrand定理.     

公共经济主体的多元化与政府治理结构的改革

20世纪70年代以来,新自由主义和西方公共经济学开始兴起。公共经济主体日益多元化,西方国家的政府治理结构出现了放任市场的转型。私人部门、第三部门、社区、国际组织纷纷成为公共经济的主体,甚至黑社会组织也为资产阶级提供公共产品。而对人民群众和社会主义国家来说,劳动者组织和公有制经济部门才是政府部门之外的最主要的公共经济主体。只要西方国家的政府还是资产阶级的政府,那么,无论其治理结构如何转型,都阻止不了政治经济危机的发生,相比之下,只有社会主义国家才有可能依靠人民群众来实现政府治理结构的改革,使国家的职能只限于几项符合普遍性、全国性目的的职能。其中比较重要的是实现政企分开,将国有资产管理委员会成建制地从各级政府划归同级人大管辖。     

Unravelling Memories of Family Separation Among Sri Lankan Tamils Resettled in Australia, 1983–2000

Abstract

Using life story interviews with 10 Sri Lankan Tamil refugees resettled in Australia, this article shows how family separation in experiences of civil war and resettlement produce long-lasting and emotional memories of fear and determination. The findings explore how young Tamil people gave meaning to family when they interacted with key individuals and negotiated cultural practices in different spaces. Moreover, intergenerational family narratives emerged as a key practice through which Tamils preserved the family identity. The analysis demonstrates how and when family separation can manifest in personal memories to reveal stories of agency and resilience. A critical engagement of the past can help to better understand concepts of childhood in relation to family and family separation in war affected diaspora communities.     

大学数学基础课教学中融入数学建模思想的实践

数学建模不仅限于解决实际问题,也可以是数学发展过程中提出的理论问题。基于近年来在大学数学基础课教学中融入数学建模思想的教学实践,论述了其主要思路与做法。介绍了将数学建模思想融入数学基础课教学的两个教学案例,即微积分方法的本质和从方程组出发引入线性相关与线性无关概念。     

Which Spouse Initiates Marital Separation When There Are Children Involved?

This report examines whether the presence of children in marriage differentially influences the risk of wives or husbands initiating separation. The analytic sample consists of 9,118 first marriages from the Households, Income and Labour Dynamics in Australia survey (2001). Using event history and competing risks analysis, I find weak evidence that wives are less likely than husbands to initiate when they have infants, and husbands are less likely than wives to initiate when children are school age or older. Overall, the results show that children deter marital separation for both wives and husbands, indicating that gender differences in the decision to separate are likely attributable to other factors such as a willingness to remain in an unhappy marriage.     

Marriage and separation risks among German cohabiters: Differences between types of cohabiter

We propose a typology of different meanings of cohabitation that combines cohabiters’ intentions to marry with a general attitude toward marriage, using competing risk analyses to examine whether some cohabiters are more prone than others to marry or to separate. Using data (N = 1,258) from four waves of the German Family Panel (PAIRFAM) and a supplementary study (DEMODIFF), we compared eastern and western German cohabiters of the birth cohorts 1971–73 and 1981–83. Western Germans more frequently view cohabitation as a step in the marriage process, whereas eastern Germans more often cohabit as an alternative to marriage. Taking into account marital attitudes reveals that cohabiters without marriage plans differ from those with plans in their relationship careers, and also shows that cohabiters who plan to marry despite holding a less favourable view of marriage are less likely to realize their plans than cohabiters whose intentions and attitudes are more congruent.     

The Frisch–Waugh–Lovell theorem for the lasso and the ridge regression

The Frisch–Waugh–Lovell (FWL) (partitioned regression) theorem is essential in regression analysis. This is partly because it is quite useful to derive theoretical results. The lasso regression and the ridge regression, both of which are penalized least-squares regressions, have become popular statistical techniques. This article describes that the FWL theorem remains valid for these penalized least-squares regressions. More precisely, we demonstrate that the covariates corresponding to unpenalized regression parameters in these penalized least-squares regression can be projected out. Some other results related to the FWL theorem in such penalized least-squares regressions are also presented.