证券投资基金业绩评价方法述评

本文详细介绍了目前证券投资基金业绩的评价方法 ,划分为财务评价方法、单位风险评价方法、业绩等级评价方法三大类别。依据现代投资组合理论 ,比较了各种方法的优缺点。最后结合我国实际 ,就存在的问题和发展方向进行了讨论。     

Influence of habitat type and distance from source area on bird taxonomic and functional diversity in a Neotropical megacity

The Neotropical region has been subjected to massive urbanization, which poses high risks for some global biodiversity hotspots and losses of ecosystem functions and services. In this study, we investigate how distance from large patches of native forests (source areas) and vegetation (green)/and infrastructure (gray) characteristics affect bird species richness and functional diversity in São Paulo megacity, southeastern Brazil. We analyzed the effects of source areas and green/gray characteristics on species richness and functional diversity (richness, evenness, and divergence) indices. We detected 231 bird species, and our data confirmed our predictions: (1) bird species richness in urbanized habitats was found to be (~?50–85%) lower than in source habitats; (2) species richness and trait composition significantly decreased as the distance from the source area increased, while functional richness was not affected by this metric; and (3) shrub and herbaceous covers and maximum height of trees were positively correlated with species richness and unique functional traits regarding habitat, diet, foraging and nesting strata and dispersal ability of birds in the forest-urban matrix. The number of buildings was negatively correlated with bird species richness and functional richness. Maximum height of buildings caused dramatic declines in functional evenness. Functional divergence was notably lower in sites with high shrub cover. Our study stresses the complexity of vegetation embedded in large Neotropical urban settlements and the need to maintain large protected areas surrounding megacities to mitigate the impacts of urbanization on birds.

     

Impact of early memories and current experiences of warmth and safeness on adolescents' psychological distress

A variable-centered and a person-centered approach were performed to examine the role of early memories of warmth and safeness (EMWS) and current experiences of warmth and safeness (CEWS) on depressive and anxious symptoms among adolescents from community and residential youth care (RYC) settings. Variable-centered results revealed EMWS were only indirectly (through CEWS) associated with depressive and anxious symptoms. Person-centered outcomes allowed to identify four different profiles based on EMWS and CEWS, which differed on depressive and anxious symptoms. EMWS and CEWS seem to play an important role in psychological distress during adolescence. CEWS seem to have a protective role on RYC adolescents' psychological distress, even when EMWS were poor.     

数字资产视角下货币法律概念的界定

以比特币为代表的数字资产是否属于货币，决定了其是否受到货币支付相关公私法律的约束。数字资产不依赖于法定货币体系、不限定使用范围、具备较强的去中心化特征，其更具独立的货币功能对货币概念界定带来了更大挑战。在既有法律仅规定人民币是法定货币以及"货币形式""货币性资产"外延的情况下，我国径行认定数字资产不是货币，未能遵循"相同业务、相同风险、相同监管"的原则，因而难以保护当事人的支付预期以及推进数字支付的进一步创新。基于国家与市场在货币流通中的定位不清、不同法律部门存在立法目的差异等因素，经济学与社会学中的货币理论难以直接用于界定货币法律概念，而法学界创造的准货币论和货币认同论在适用范围、前置条件等方面亦存在诸多局限。现代货币支付体系已形成以法定货币作为基础、以法定货币计价的支付手段多样化发展，以及不以法定货币计价的支付手段共存的分层特征。货币分层体系本质是国家与市场、公共与私人的混合体，国家处于该体系的顶端，而法定货币则成为信用程度最高的货币类型。在该分层体系下，货币法律概念不具有同一性，更不能仅限于法定货币，而应将货币的法律内涵确定为用于清偿货币债务的，可以被普遍接受的"支付系统要素"，以区分于投资工具、货币载体及仅少数人或小区域内认可的支付手段。其中，可参考反垄断法中的相关市场和市场份额的理论内容，从子服务市场、使用权限、可替代的另一货币认定被普遍接受的市场范围，并通过币值稳定机制和接受货币的商家数量认定普遍接受的程度。另外，货币的法律外延包括在宪法与中央银行法中具有法定偿付效力的法定货币，以及在支付服务法、反洗钱法中具有支付监管效力，或在财产保护、行政费用征缴法律中具有货币财产效力的其他支付手段。其中，随着数字资产和法定数字货币的兴起，货币分层体系的构成更为丰富，具有支付监管效力和货币财产效力的货币数量将愈发增多。