Publications by authors named "F S Nielsen"

Background: Per- and poly-fluoroalkyl Substances (PFAS) have been used for decades in countless households and industrial products. Many PFAS do not degrade and are thus ubiquitous in the environment and within organisms. Humans are primarily exposed to PFAS through ingestion and inhalation, and such exposure has been associated with several health effects.

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Background: Over the past decade, the use of organophosphate insecticides including chlorpyrifos has faced increasing restrictions due to health concerns, leading to a rise in use of pyrethroids. Concerns about neurodevelopmental insults following pyrethroids exposure exist, but few studies have examined the long-term effects of childhood exposure to chlorpyrifos and pyrethroids on IQ.

Objective: To investigate the prospective associations between pyrethroids and chlorpyrifos exposure at age 5 years and IQ scores assessed at age 7.

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Symplectic Bregman Divergences.

Entropy (Basel)

December 2024

We present a generalization of Bregman divergences in finite-dimensional symplectic vector spaces that we term symplectic Bregman divergences. Symplectic Bregman divergences are derived from a symplectic generalization of the Fenchel-Young inequality which relies on the notion of symplectic subdifferentials. The symplectic Fenchel-Young inequality is obtained using the symplectic Fenchel transform which is defined with respect to the symplectic form.

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The symmetric Kullback-Leibler centroid, also called the Jeffreys centroid, of a set of mutually absolutely continuous probability distributions on a measure space provides a notion of centrality which has proven useful in many tasks, including information retrieval, information fusion, and clustering. However, the Jeffreys centroid is not available in closed form for sets of categorical or multivariate normal distributions, two widely used statistical models, and thus needs to be approximated numerically in practice. In this paper, we first propose the new Jeffreys-Fisher-Rao center defined as the Fisher-Rao midpoint of the sided Kullback-Leibler centroids as a plug-in replacement of the Jeffreys centroid.

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An environmentally compatible and less costly (greener) analytical method for the digestion of bone meal samples using microwave-assisted dilute nitric acid (HNO) was developed and optimized. The method, employing a mixture of 1 mL concentrated HNO and 4 mL of deionized water, offered a comparable performance to the conventional method using 5 mL of concentrated HNO. The accuracy of the method was validated by using certified reference material NIST 1486 (Bone Meal); percentage recoveries were within ±15% for all eight certified elements.

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