Bell correlations outside physics.

Correlations are ubiquitous in nature and their principled study is of paramount importance in scientific development. The seminal contributions from John Bell offer a framework for analyzing the correlations between the components of quantum mechanical systems and have instigated an experimental tradition which has recently culminated with the Nobel Prize in Physics (2022). In physics, Bell's framework allows the demonstration of the non-classical nature of quantum systems just from the analysis of the observed correlation patterns. Bell's ideas need not be restricted to physics. Our contribution is to show an example of a Bell approach, based on the insight that correlations can be broken down into a part due to common, ostensibly significant causes, and a part due to noise. We employ data from finance (price changes of securities) as an example to demonstrate our approach, highlighting several general applications: first, we demonstrate a new measure of association, informed by the assumed causal relationship between variables. Second, our framework can lead to streamlined Bell-type tests of widely employed models of association, which are in principle applicable to any discipline. In the area of finance, such models of association are Factor Models and the bivariate Gaussian model. Overall, we show that Bell's approach and the models we consider are applicable as general statistical techniques, without any domain specificity. We hope that our work will pave the way for extending our general understanding for how the structure of associations can be analyzed.

Histiocytic necrotising lymphadenitis in mediastinum mimicking thymoma or lymphoma - case presentation and literature review of Kikuchi Fujimoto disease.

Kikuchi Fujimoto disease (KFD) as a rare self-limiting lymphadenopathy of short and benign course concerns most frequently the lymph nodes of the neck. The most common symptoms are painfulness of the diseased area, fever and night sweating. The etiology is not well understood, but in the role of pathogenesis viral, autoimmune and genetic factors are taken into account. In the presented case of 37-year-old female it was necessary to exclude diseases such as lymphoma or thymoma because of atypical mediastinal location of Kikuchi Fujimoto disease. After multidisciplinary consultation the lymph node was resected from the mediastinum with videothoracoscopic approach. The diagnosis was difficult for the pathologist because of the large percentage of necrosis of the lymph node but the image was typical for histiocytic necrotizing lymphadenitis. Two cases of patients with KFD limited to the mediastinum have been previously reported in the literature. This article presents the world's first reported case of this disease in the topographic location of the thymus. Furthermore, a review of current literature was made.