On the Benefits of Equicorrelation for Portfolio Allocation

The importance of modelling correlation has long been recognised in the field of portfolio management, with large‐dimensional multivariate problems increasingly becoming the focus of research. This paper provides a straightforward and commonsense approach toward investigating a number of models used to generate forecasts of the correlation matrix for large‐dimensional problems. We find evidence in favour of assuming equicorrelation across various portfolio sizes, particularly during times of crisis. During periods of market calm, however, the suitability of the constant conditional correlation model cannot be discounted, especially for large portfolios. A portfolio allocation problem is used to compare forecasting methods. The global minimum variance portfolio and Model Confidence Set are used to compare methods, while portfolio weight stability and relative economic value are also considered. Copyright © 2015 John Wiley & Sons, Ltd.     

Biochemical differentiation in the Idaho ground squirrel, Spermophilus brunneus (Rodenta: Scuridae)

Spermophilus brunneus is restricted to a 90 × 125-km area of west central Idaho, with two distinct (northern and southern) groups of populations within this limited range. Morphological differences in pelage length and coloration, external and cranial measurements, and bacula suggest that these groups are either very distinct subspecies or species. We used starch-gel electrophoresis to estimate the amount of genetic differentiation accompanying these morphological differences by assaying genetic variation at 31 loci in the two geographic groups. Fifteen loci were polymorphic (13 in the northern group, 12 in the southern), and mean heterozygosity (H) was high (12.3% northern and 10.8% southern). Nei's genetic distance (0.057) is in the range usually associated with subspecific differences. However, Jaccard's association coefficient (0.893) is about the same as that found between several ground squirrel taxa currently recognized as species. The high levels of heterozygosity suggest that S. brunneus is a neoendemic rather than a paleoendemic species.     

SARS-CoV-2 nucleocapsid protein: Importance in viral infection

The coronavirus disease 2019 (COVID-19) epidemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused millions of deaths worldwide. Therefore, it is critical to understand the biological basis of SARS-CoV-2 to develop novel approaches to control its spread. The SARS-CoV-2 nucleocapsid (N) protein is an important diagnostic and potent therapeutic target of the disease, as it is involved in numerous important functions in the viral life cycle. Several studies have explained the structural and functional aspects of the SARS-CoV-2 N protein. This review summarizes the currently available data on the evolutionarily conserved N protein of SARS-CoV-2 by providing detailed information on the structural and multifunctional characteristics of the N protein.