论驯鹿鄂温克人的兽皮文化

生活在大兴安岭中的驯鹿鄂温克人是鄂温克族中的独特群体,千百年来一直以饲养驯鹿和森林游猎为生。他们在特定的自然环境、特殊的生存条件以及特有的生产生活中,创造出了适合于他们物质文明和精神文明的兽皮文化。     

Multiple tests for the performance of different investment strategies

In the context of modern portfolio theory, we compare the out-of-sample performance of eight investment strategies which are based on statistical methods with the out-of-sample performance of a family of trivial strategies. A?wide range of approaches is considered in this work, including the traditional sample-based approach, several minimum-variance techniques, a shrinkage, and a minimax approach. In contrast to similar studies in the literature, we also consider short-selling constraints and a risk-free asset. We provide a way to extend the concept of minimum-variance strategies in the context of short-selling constraints. A main drawback of most empirical studies on that topic is the use of simple testing procedures which do not account for the effects of multiple testing. For that reason we conduct several hypothesis tests which are proposed in the multiple-testing literature. We test whether it is possible to beat a trivial strategy by at least one of the non-trivial strategies, whether the trivial strategy is better than every non-trivial strategy, and which of the non-trivial strategies is significantly outperformed by naive diversification. The empirical part of our study is conducted using US stock returns from the last four decades, obtained via the CRSP database.     

Linear statistical inference for global and local minimum variance portfolios

Traditional portfolio optimization has often been criticized for not taking estimation risk into account. Estimation risk is mainly driven by the parameter uncertainty regarding the expected asset returns rather than their variances and covariances. The global minimum variance portfolio has been advocated by many authors as an appropriate alternative to the tangential portfolio. This is because there are no expectations which have to be estimated and thus the impact of estimation errors can be substantially reduced. However, in many practical situations an investor is not willing to choose the global minimum variance portfolio but he wants to minimize the variance of the portfolio return under specific constraints for the portfolio weights. Such a portfolio is called local minimum variance portfolio. Small-sample hypothesis tests for global and local minimum variance portfolios are derived and the exact distributions of the estimated portfolio weights are calculated in the present work. The first two moments of the estimator for the expected portfolio returns are also provided and the presented instruments are illustrated by an empirical study.     

Neoliberal motherhood during the pandemic: Some reflections

In this article, I argue that there are at least three essential elements that inform the idealized mother figure today and I reflect upon the effects the COVID‐19 pandemic has on each of these elements. The three essential elements in the contemporary understanding of motherhood reflect neoliberal concerns and are related to mothers’ unpaid work, the female body and mothers’ participation in the labour market. These three elements have been distilled with the help of secondary literature and are based on initial observations and interview results that had been conducted as part of an ongoing research project on contemporary motherhood practices of upper‐middle‐class mothers from Switzerland, Turkey and Germany. Consequently, the focus in this article lies on upper‐class and upper‐middle‐class women. In contrast to optimistic visions that envision the end of neoliberalism, I argue that the neoliberal understanding of motherhood is likely to persist and to re‐emerge as the dominant model of motherhood in the wake of the pandemic.     

Family Support in Nursing Homes Serving Residents with a Mental Health History

Using 2003 nursing home data from the Minimum Data Set (MDS) database, this study investigated the role of family support among nursing homes serving residents with a mental health history. Exploratory factor analysis was used to create and test a conceptual model of family support using indicators located within the MDS database. Families were found to be in regular contact with their relatives and supportive of their care. In nursing homes, daily contact, an ongoing relationship, involvement in assessment, and being responsible for the resident constitute the model family support. This study advances the understanding of family support in nursing homes and conveys information to guide practice through proposing ways to enhance family support and involvement in nursing homes.     

驯鹿鄂温克人的萨满教文化

驯鹿鄂温克人信奉的萨满教,集自然崇拜、图腾崇拜、祖先崇拜之大成,以万物有灵的信仰为其思想意识的基础。萨满教文化作为驯鹿鄂温克人传统文化的核心,渗透于他们社会生活的方方面面。