A tracking system for determining the five-degrees-of-freedom position and orientation of a cylindrical permanent magnet was developed. The system consists of a planar array of 27 Hall effect ...magnetic sensors, interface electronics, and computer. A magnet is modeled by an ideal magnetic dipole. The closed-form solution for the magnetic flux density of the magnetic dipole was used with a Levenberg-Marquardt optimization algorithm to determine the coordinates of the dipole. The system was characterized using Nd-Fe-B magnets (n=5,B r =14.25plusmn0.25 kG, 2.00-mm diameter D, and 5.00-mm length L and n=5,B r =13.1plusmn0.1 kG, 4.55-mm D, and 6.35-mm L). The axis of each magnet was first aligned perpendicular to the center of the sensor array, and an automated positioner moved the magnet away from the array perpendicular to its face. Voltage data was collected from the 27 sensors at each 1-mm interval along this direction out to 150 mm for the smaller magnets and 300 mm for the larger magnets. Sensor offset and environmental magnetic flux density were measured after each test. A coordinate measurement machine verified the position and orientation of the magnets. A useful range of 100 mm from the array was determined for all magnets tested. Within this range, the position of smaller magnets along the axis of motion were determined with maximum error of 1.8 mm, while their position in the two orthogonal directions perpendicular to the axis of motion were determined with maximum error of 5.3 mm; the position of larger magnets along the axis of motion were determined with maximum error of 0.8 mm, while their position in the two orthogonal directions were determined with maximum error of 3.8 mm; and the maximum error in orientation for all magnets tested was 4.2deg
Abstract
Patients with severe COVID-19 experience cytokine storm, an uncontrolled upregulation of pro-inflammatory cytokines, which if unresolved leads to acute respiratory distress syndrome (ARDS), ...organ damage, and death. Treatments with mesenchymal stromal cells (MSC) Viswanathan S, Shi Y, Galipeau J, et al. Mesenchymal stem versus stromal cells: International Society for Cell & Gene Therapy Mesenchymal Stromal Cell committee position statement on nomenclature. Cytotherapy. 2019;21:1019-1024 appear to be effective in reducing morbidity and mortality. MSC respond to pro-inflammatory cytokines by releasing anti-inflammatory factors and mobilizing immune cells. We analyzed 82 COVID-19 clinical trials registered at ClinicalTrials.gov to determine MSC dosing, routes of administration, and outcome measures. Nearly all trials described the use of intravenous delivery with most doses ranging between 50 and 125 million MSC/treatment, which overlaps with a minimal effective dose range that we described previously. We also searched the literature to analyze clinical trial reports that used MSC to treat COVID-19. MSC were found to improve survival and oxygenation, increase discharge from intensive care units and hospitals, and reduce levels of pro-inflammatory markers. We report on a 91-year-old man with severe COVID-19 who responded rapidly to MSC treatment with transient reductions in several pro-inflammatory markers and delayed improvement in oxygenation. The results suggest that frequent monitoring of pro-inflammatory markers for severe COVID-19 will provide improved treatment guidelines by determining relationships between cytokine storms and ARDS. We propose that markers for cytokine storm are leading indicators for ARDS and that measurement of cytokines will indicate earlier treatment with MSC than is performed now for ARDS in severe COVID-19.
