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.     

A probabilistic epidemiological model for infectious diseases: The case of COVID-19 at global-level

This study has developed a probabilistic epidemiological model a few weeks after the World Health Organization declared COVID-19 a pandemic (based on the little data available at that time). The aim was to assess relative risks for future scenarios and evaluate the effectiveness of different management actions for 1 year ahead. We quantified, categorized, and ranked the risks for scenarios such as business as usual, and moderate and strong mitigation. We estimated that, in the absence of interventions, COVID-19 would have a 100% risk of explosion (i.e., more than 25% infections in the world population) and 34% (2.6 billion) of the world population would have been infected until the end of simulation. We analyzed the suitability of model scenarios by comparing actual values against estimated values for the first 6 weeks of the simulation period. The results proved to be more suitable with a business-as-usual scenario in Asia and moderate mitigation in the other continents. If everything went on like this, we would have 55% risk of explosion and 22% (1.7 billion) of the world population would have been infected. Strong mitigation actions in all continents could reduce these numbers to, 7% and 3% (223 million), respectively. Although the results were based on the data available in March 2020, both the model and probabilistic approach proved to be practicable and could be a basis for risk assessment in future pandemic episodes with unknown virus, especially in the early stages, when data and literature are scarce.     

Levels or worlds of welfare? Assessing social rights and social stratification in Northern and Southern countries

Since Esping‐Andersen's Three Worlds, it has become a truism of welfare state research that welfare states do not vary linearly along a single dimension but have to be conceptualized as multidimensional phenomena that cluster into types caused by the political economy of class coalitions. However, when moving beyond the 18 original countries of Esping‐Andersen's analysis, the situation is less clear. Although additional worlds have been identified in the Global North and the Global South, these are usually not conceptualized along the same dimensions as the original three worlds and are rarely empirically compared with them. This paper tackles these omissions by explicitly comparing Northern and Southern countries within Esping‐Andersen's framework. It poses the question whether the central insight of welfare state research, namely, that there are not just gradual differences between welfare states, but different types with qualitative differences, expands beyond classic welfare states. Based on newly generated data on social rights and social stratification, we employ cluster analysis with 45 Northern and Southern countries. This analysis produces mixed results. We do find different types of welfare states with qualitative differences, but these do not fully correspond to Esping‐Andersen's Three Worlds. Moreover, our findings also point to a conceptual issue in welfare regime research: regimes are not just defined and measured in terms of different logics of welfare provision but also take into account degrees of welfare stateism. We argue that this issue is poised to become ever more pressing with the geographical expansion of welfare state research.     

Caloric restriction minimizes aging effects on the femoral medial condyle

This study aimed to analyze the effects of caloric restriction on aged femoral articular cartilage of Wistar rats. Three groups of eight animals each were considered: young (YC) and old (OC) control groups fed with a normal diet and old caloric restriction group (OCR) composed of 18-month-old animals fed with a 31% less caloric diet from 6-months of age. Articular cartilage was studied through morphometry and immunohistochemistry. Body mass was 12% less in the OCR group than in the OC group. The articular cartilage from OC rats show thinner medial condyles, fewer chondrocytes, smaller chondrocytes nuclear volume and, in both condyles, a predominance of collagen type II and less collagen density compared to both YC and OCR groups (p?p?相似文献   

Looking Forward in Candidate Gene Research: Concerns and Suggestions

Candidate Gene × Environment (cGxE) interaction research holds promise for helping us understand for whom and why environments matter for families and development. In their commentary on our target article (G. L. Schlomer, G. M. Fosco, H. H. Cleveland, D. J. Vandenbergh, & M. E. Feinberg, 2015), J. E. Salvatore and D. M. Dick (2015) present their view of the current state and future of cGxE research and frame the debate regarding its merits for advancing knowledge of gene–environment interplay. In this reply, we discuss points of agreement and departure and provide a list of 5 domains by which the quality of cGxE research should be evaluated. Our hope is that researchers will use this list as a guide for their own work.     

Beyond ‘developmentalism’: A relational and embodied approach to young children's development

This article begins by discussing ‘developmentalism’, one of the key debates that has characterised the current theoretical impasse in the development of childhood studies. I use Norbert Elias's concept of the relation between love and learning as a foundation to develop the way in which young children's development is a non-linear, temporal and embodied process. I argue that we need to develop a relational approach that moves beyond some of the binary divisions between ‘nature’ and ‘biology’, drawing on concepts from particular theoretical traditions that have been under-utilised, particularly the relational school of psychoanalysis and the work of Maurice Merleau-Ponty.     

Longitudinal Links between Adolescent and Peer Conduct Problems and Moderation by a Sensitivity Genetic Index

The most extensively studied influence on adolescent conduct problem behaviors is peers, and the literature points to genetics as one source of individual differences in peer influence. The purpose of this study was to test the hypothesis that an environmental sensitivity genetic index comprised of DRD4, 5‐HTTLPR, and GABRA2 variation would moderate the association between peer and adolescent conduct problems. Latent growth modeling was applied to PROSPER project longitudinal data from adolescents and their peers. Results showed the hypothesis was supported; adolescents with more copies of putative sensitivity alleles were more strongly influenced by their peers. The interaction form was consistent with differential susceptibility in follow‐up analyses. Strengths and weaknesses of genetic aggregates for sensitivity research are discussed.     

Connecting and Strengthening Young Aboriginal Men: A Family Wellbeing Pilot Study

A significant proportion of young people in Australia are currently not being engaged in school and other social systems. This article presents the results of a mixed-methods study of a pilot Family Wellbeing intervention designed to enhance the social and emotional wellbeing (SEWB) of young Aboriginal men and improve engagement in education, employment, and other social participation. A questionnaire incorporating the Kessler Psychological Distress Scale and respondent self-assessment SEWB questions was administered to program participants pre and post intervention (N = 30) and qualitative data were collected from program organisers (N = 6). The results suggest that the Family Wellbeing intervention has the capacity to make a marked contribution to the SEWB of young Aboriginal men; participants experienced strong improvement in capacity to manage relationships, engagement in education and employment, and mental and physical health. The factors that enabled the program to be adapted to the target group and setting are documented.     

A reconsideration of the tradeoffs in the new human development index

This paper demonstrates that the perfect tradeoff implication of the old Human Development Index can be avoided by employing a notion of imperfect tradeoff in the characterization of the Human Development Index. The resulting index is shown to be ordinally equivalent to the Chakravarty (Rev Dev Econ 7:99–114, 2003) generalized Human Development Index.