The Evaluation of the Impact of a Saharan Event on Particulate Matter Using Compositional Data Analysis

The proposed approach based on compositional data analysis was applied on simultaneous measurements of the mineral element concentrations of PM10 and PM2.5 from a typical suburban site with and without a Saharan event. The suburban site is located in the city of Rome. The selected mineral elements were Al, Si, Ca, Fe, Ti, Mg, and Sr. The data relating to these elements are reported in a previous study. The considered elements are mainly related to mineral matter. The proposed approach allows statistically validating that the mineral element concentrations of PM during days with a Saharan event differ from those without a Saharan event in terms of mineral element composition and size distribution. In particular, the results showed that the compositional data analysis applied to simultaneous measurements of mineral element concentrations of PM10 and PM2.5 is a helpful technique that can be used to study environmental sites affected by natural sources such as Saharan events. Moreover, the presented technique can be handy in all those conditions where it is important to discriminate whether the occurrence of an exceedance or a violation of the daily limit value established for PM could also be due to natural sources.

Comparison of Repetitive Cardiac Output Measurements at Rest and End-Exercise by Direct Fick Using Pulse Oximetry vs. Blood Gases in Patients With Pulmonary Hypertension

Background: Exact and simultaneous measurements of mean pulmonary artery pressure (mPAP) and cardiac output (CO) are crucial to calculate pulmonary vascular resistance (PVR), which is essential to define pulmonary hypertension (PH). Simultaneous measurements of mPAP and CO are not feasible using the direct Fick (DF) method, due to the necessity to sample blood from the catheter-tip. We evaluated a modified DF method, which allows simultaneous measurement of mPAP and CO without needing repetitive blood samples.Methods: Twenty-four patients with pulmonary arterial or chronic thromboembolic PH had repetitive measurements of CO at rest and end-exercise during three phases of a crossover trial. CO was assessed by the original DF method using oxygen uptake, measured by a metabolic unit, and arterial and mixed venous oxygen saturations from co-oximetry of respective blood gases served as reference. These CO measurements were then compared with a modified DF method using pulse oximetry at the catheter- and fingertip.Results: The bias among CO measurements by the two DF methods at rest was −0.26 L/min with limits of agreement of ±1.66 L/min. The percentage error was 28.6%. At the end-exercise, the bias between methods was 0.29 L/min with limits of agreement of ±1.54 L/min and percentage error of 16.1%.Conclusion: Direct Fick using a catheter- and fingertip pulse oximetry (DFp) is a practicable and reliable method for assessing CO in patients with PH. This method has the advantage of allowing simultaneous measurement of PAP and CO, and frequent repetitive measurements are needed during exercise.Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT02755259, identifier: NCT02755259.

Four-electrode probe for plasma studies in the GOL-NB multiple-mirror trap

A system of four-electrode Langmuir probes developed for the GOL-NB multiple-mirror trap is discussed. The system is used for studies of a low-temperature start plasma (1019–1020 m-3, 5 eV) that fills the device during the initial phase of the experiment. The probe allows simultaneous measurements of plasma density, electron temperature and radial electric field. The accuracy of the probe measurements is also discussed.