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Estimation methods for a linearly structured covariance matrix
Summary Covariance matrices with a linear structure are widely used in multivariate analysis. The choice of the most appropriate covariance structure can be made from a class of possible linear structures. Once we have made the choice, an important question is how we can estimate the covariance matrix for a given covariance structure. This article describes methods used to estimate the structured covariance matrix, and indicates the advantages and disadvantages of the selected methods.
Structure identification for a linearly structured covariance matrix: part II
Summary Covariance matrices with a linear structure are widely used in multivariate analysis. The choice of covariance structure can be made from a set of possible linear structures. As a result, the most appropriate structure is determined by minimizing the discrepancy function. This paper is a continuation of previous work on identifying linear structures with an entropy loss function as a discrepancy function. We present extensive simulation studies on the correctness of identification with the assumed pentagonal banded Toeplitz structure.
The tissue distribution of nucleobindin-2/nesfatin-1 in the reproductive organs of bitches with regard to the animal’s age and body weight
Abstract Introduction Neuropeptide nesfatin-1, a nucleobindin-2 derivative, plays a role in regulating food intake, energy metabolism and body weight. It also interacts with the hypothalamic-pituitary-gonadal axis and has functions in the reproductive system. However, its impact on the canine reproductive tract has not been well documented. This study aimed to investigate the potential role of nesfatin-1 in canine ovarian activity and uterine function. Material and Methods Tissue and peripheral blood samples were collected from 60 bitches of various ages and body condition scores (BCS). Analyses included real-time PCR, immunofluorescence examinations and ELISA tests. Results Higher level of nucleobindin-2 mRNA were found in the ovarian tissue of both younger and elderly overweight dogs (BCS > 5/9). The elevated expression of nesfatin-1 was observed in the uterine tissues of overweight dogs (BCS > 5/9) compared to its expression in animals in optimal body condition (BCS = 4/9). This finding was consistent with higher nesfatin-1 levels in the peripheral blood of overweight dogs. Conclusion The distribution and expression of nesfatin-1 in canine reproductive organs vary depending on the animal’s age and body weight. The role of nesfatin-1 in the reproductive system is influenced by the animal’s body condition and the extent of surplus adipose tissue, which may have significant implications for reproductive functions.