Evaluation of the Linear Relationship Between Pulse Arrival Time and Blood Pressure in ICU Patients: Potential and Limitations

A variety of techniques based on the indirect measurement of blood pressure (BP) by Pulse Transit Time (PTT) have been explored over the past few years. Such an approach has the potential in providing continuous and non-invasive beat to beat blood pressure without the use of a cuff. Pulse Arrival Time (PAT) which includes the cardiac pre-ejection period has been proposed as a surrogate of PTT, however, the balance between its questioned accuracy and measurement simplicity has yet to be established. The present work assessed the degree of linear relationship between PAT and blood pressure on 96 h of continuous electrocardiography and invasive radial blood pressure waveforms in a group of 11 young ICU patients. Participants were selected according to strict exclusion criteria including no use of vasoactive medications and presence of clinical conditions associated with cardiovascular diseases. The average range of variation for diastolic BP was 60 to 79 mmHg while systolic BP varied between 123 and 158 mmHg in the study database. The overall Pearson correlation coefficient for systolic and diastolic blood pressure was −0.5 and −0.42, respectively, while the mean absolute error was 3.9 and 7.6 mmHg. It was concluded that the utilization of PAT for the continuous non-invasive blood pressure estimation is rather limited according to the experimental setup, nonetheless the correlation coefficient performed better when the range of variation of blood pressure was high over periods of 30 min suggesting that PAT has the potential to be used as indicator of changes relating to hypertensive or hypotensive episodes

Oxygen photolysis in the Mauritanian upwelling: Implications for net community production

We carried out 16 photochemical experiments of filtered surface water in a custom-built solar simulator and concomitant measurements of in vitro gross primary production (GPP) and respiration (R) in the Mauritanian upwelling during a Lagrangian study following three sulfur hexafluoride–labeled patches of upwelled water (P1 to P3). Oxygen photolysis rates were correlated with the absorbance of chromophoric dissolved organic matter (CDOM) at 300 nm, suggesting first-order kinetics with respect to CDOM. An exponential fit was used to calculate the apparent quantum yield (AQY) for oxygen photolysis, giving an average AQY of 0.00053 mmol O2 (mole photons m22 s21)21 at 280 nm and slope of 0.0012 nm21. Modeled photochemical oxygen demand (POD) at the surface (3–16 mmol m23 d21) occasionally exceeded R and was dominated by ultraviolet radiation (71– 79%). Euphotic-layer integrated GPP decreased with time during both P-1 and P-3, whereas R remained relatively constant and POD increased during P-1 and decreased during P-3. On Day 4 of P-3, GPP and POD maxima coincided with high CDOM absorbance, suggesting ‘‘new’’ CDOM production. Omitting POD may lead to an underestimation of net community production (NCP), both through in vitro and geochemical methods (here by 2–22%). We propose that oxygen-based NCP estimates should be revised upward. For the Mauritanian upwelling, the POD-corrected NCP was strongly correlated with standard NCP with a slope of 1.0066 6 0.0244 and intercept of 46.51 6 13.15 mmol m22 d21

Hall field induced magnetoresistance oscillations of a two-dimensional electron system

We develop a model of the nonlinear response to a DC electrical current of a two dimensional electron system(2DES) placed on a magnetic field. Based on the exact solution of the Schroedinger equation in arbitrarily strong electric and magnetic fields, and separating the relative and guiding center coordinates, a Kubo-like formula for the current is worked out as a response to the impurity scattering. Self-consistent expressions determine the longitudinal and Hall components of the electric field in terms of the DC current. The differential resistivity displays strong Hall field-induced oscillations, in agreement with the main features of the phenomenon observed in recent experiments.Comment: 11 pages, 5 figure

The time for bibliometric applications

Early view DOI: 10.1002/asi.23604This letter to the editor proposes the introduction of smartphones apps to develop new bibliometrics tools and products based on the success of the development of UGRinvestiga from the University of Granada

Global Evolution of Research on Silvopastoral Systems through Bibliometric Analysis: Insights from Ecuador

Scientific studies on silvopastoral systems have led to permanent changes oriented toward better silvopasture practices, as well as to policy strategies to respond effectively to the global objectives of restoration and sustainable development. In this work, we performed a bibliometric analysis with the purpose of identifying changes associated with different silvopastoral systems. We applied Bibliometrix in R to analyze 5708 documents published between 1983 and 2022 by including the terms “silvopastoral” and “silvopasture”, among others. The results showed a longitudinal and exponential increase in silvopasture studies over the last 20 years. We adjusted the growth to an S-Curve function with an R2 of 96.06%. The interest of researchers regarding knowledge about silvopasture has evolved; initially, it focused on the characterization of silvopasture, whereas recently, it has focused on the search for strategies to improve the sustainable use of silvopasture, including ecosystem restoration and the implementation of better practices. The following countries stand out as those with the largest scientific production of studies on silvopasture: The United States, Brazil, Mexico, Colombia, and Argentina in the Americas; China and India in Asia; and Spain; and Germany, and the United Kingdom in Europe. In the case of Ecuador, cited leaders in silvopasture facilitated the construction of a group of experts who contribute to the development of public policies. The most cited publications appeared in journals published by the Springer group, Elsevier, and MDPI Journals, mostly in open-access systems. In the future, the disruptive contribution of open-access systems in the global dissemination of knowledge, breaking through the economic constraints of countries, universities, and researchers, should be evaluated