Thomas, Leslie F.

Abstract Most current algorithms for multivariate time series classification tend to overlook the correlations between time series of different variables. In this research, we propose a framework that leverages Eigen-entropy along with a cumulative moving window to derive time series signatures to support the classification task. These signatures are enumerations of correlations among different time series considering the temporal nature of the dataset. To manage dataset's dynamic nature, we employ preprocessing with dense multi scale entropy. Consequently, the proposed framework, Eigen-entropy-based Time Series Signatures, captures correlations among multivariate time series without losing its temporal and dynamic aspects. The efficacy of our algorithm is assessed using six binary datasets sourced from the University of East Anglia (UEA), in addition to a publicly available sepsis dataset and an institutional sepsis dataset from the Mayo Clinic. We employ recall as a metric for evaluation against the baseline algorithm, Dependent Dynamic Time Warping with 1 Nearest Neighbor. Our algorithm outperforms the baseline algorithm for UEA datasets in terms of recall with an average value of 10% across all datasets, and by 38% for an institutional sepsis dataset. For the public sepsis dataset, the performance of our algorithm is comparable to the baseline algorithm.

Colorimetric sensors are widely used because of their inherent advantages including accuracy, rapid response, ease-of-use, and low costs; however, they usually lack reusability, which precludes the continuous use of a single sensor. We have developed a threshold-responsive colorimetric system that enables repeated analyte measurements by a single colorimetric sensor. The threshold responsive algorithm automatically adjusts the sensor exposure time to the analyte and measurement frequency according to the sensor response. The system registers the colorimetric sensor signal change rate, prevents the colorimetric sensor from reaching saturation, and allows the sensor to fully regenerate before the next measurement is started. The system also addresses issues common to colorimetric sensors, including the response time and range of detection. We demonstrate the benefits and feasibility of this novel system, using colorimetric sensors for ammonia and carbon dioxide gases for continuous monitoring of up to (at least) 60 detection cycles without signs of analytical performance degradation of the sensors.

The mechanisms by which phosphorus homeostasis is preserved in mammals are not completely understood. We demonstrate the presence of a mechanism by which the intestine detects the presence of increased dietary phosphate and rapidly increases renal phosphate excretion. The mechanism is of physiological relevance because it maintains plasma phosphate concentrations in the normal range after ingestion of a phosphate-containing meal. When inorganic phosphate is infused into the duodenum, there is a rapid increase in the renal fractional excretion of phosphate (FE Pi). The phosphaturic effect of intestinal phosphate is specific for phosphate because administration of sodium chloride does not elicit a similar response. Phosphaturia after intestinal phosphate administration occurs in thyro-parathyroidectomized rats, demonstrating that parathyroid hormone is not essential for this effect. The increase in renal FE Pi in response to the intestinal administration of phosphate occurs without changes in plasma concentrations of phosphate (filtered load), parathyroid hormone, FGF-23, or secreted frizzled related protein-4. Denervation of the kidney does not attenuate phosphaturia elicited after intestinal phosphate administration. Phosphaturia is not elicited when phosphate is instilled in other parts of the gastrointestinal tract such as the stomach. Infusion of homogenates of the duodenal mucosa increases FE Pi, which demonstrates the presence of one or more substances within the intestinal mucosa that directly modulate renal phosphate reabsorption. Our experiments demonstrate the presence of a previously unrecognized phosphate gut–renal axis that rapidly modulates renal phosphate excretion after the intestinal administration of phosphate.