An adequate strategy for the thermodilution technique in patients during mechanical ventilation

The application of the thermodilution method in conditions associated with variations in blood flow implies a misuse of the Stewart Hamilton equation. Therefore, we studied the reliability of the thermodilution method for the estimation of mean cardiac output (CO) during mechanical ventilation in patients (n=9). Variation of the injection moment in the ventilatory cycle elicited a cyclic variation of CO estimates. This variation was not the same for all patients neither in phase nor in amplitude. Therefore, no specific phase in the ventilatory cycle could be selected for an accurate estimation of mean CO. Averaging CO estimates randomly distributed in the ventilatory cycle led to an improvement of accuracy with the square root of the number of observations. The averaging of CO estimates spread equally over the ventilatory cycle led to a much better result, e.g., the variation in the average of two estimates equally spread in the ventilatory cycle was similar to the variation in the average of four random estimates. We conclude that averaging of 3 or 4 estimates spread equally over the ventilatory cycle is an adequate strategy to estimate mean cardiac output in patients reliably

The problem of a metal impurity in an oxide: ab-initio study of electronic and structural properties of Cd in Rutile TiO2

In this work we undertake the problem of a transition metal impurity in an oxide. We present an ab-initio study of the relaxations introduced in TiO2 when a Cd impurity replaces substitutionally a Ti atom. Using the Full-Potential Linearized-Augmented-Plane-Wave method we obtain relaxed structures for different charge states of the impurity and computed the electric-field gradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are dependent on the charge state of the impurity. This dependence is very remarkable in the case of the EFG and is explained analyzing the electronic structure of the studied system. We predict fairly anisotropic relaxations for the nearest oxygen neighbors of the Cd impurity. The experimental confirmation of this prediction and a brief report of these calculations have recently been presented [P.R.L. 89, 55503 (2002)]. Our results for relaxations and EFGs are in clear contradiction with previous studies of this system that assumed isotropic relaxations and point out that no simple model is viable to describe relaxations and the EFG at Cd in TiO2 even approximately.Comment: 11 pages, 8 figures, Revtex 4, published in Physical Review

In vitro efficacy of artemisinin-based treatments against SARS-CoV-2

Effective and affordable treatments for patients suffering from coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are needed. We report in vitro efficacy of Artemisia annua extracts as well as artemisinin, artesunate, and artemether against SARS-CoV-2. The latter two are approved active pharmaceutical ingredients of anti-malarial drugs. Concentration–response antiviral treatment assays, based on immunostaining of SARS-CoV-2 spike glycoprotein, revealed that treatment with all studied extracts and compounds inhibited SARS-CoV-2 infection of VeroE6 cells, human hepatoma Huh7.5 cells and human lung cancer A549-hACE2 cells, without obvious influence of the cell type on antiviral efficacy. In treatment assays, artesunate proved most potent (range of 50% effective concentrations (EC50) in different cell types: 7–12 µg/mL), followed by artemether (53–98 µg/mL), A. annua extracts (83–260 µg/mL) and artemisinin (151 to at least 208 µg/mL). The selectivity indices (SI), calculated based on treatment and cell viability assays, were mostly below 10 (range 2 to 54), suggesting a small therapeutic window. Time-of-addition experiments in A549-hACE2 cells revealed that artesunate targeted SARS-CoV-2 at the post-entry level. Peak plasma concentrations of artesunate exceeding EC50 values can be achieved. Clinical studies are required to further evaluate the utility of these compounds as COVID-19 treatment

Mental fatigue after very severe closed head injury: Sustained performance, mental effort, and distress at two levels of work-load in a driving simulator

In patients with very severe closed head injury (CHI), returning to work is often problematic. The present study focuses on a persistent complaint of these patients, viz. mental fatigue. To study this, the effect of sustained workload is assessed in a continuous dynamic divided attention task. Three types of measures are employed: performance loss with time-on-task, and subjective reports and cardiovascular measures of mental effort and distress. Eight very severe CHI patients (mean post-traumatic amnesia duration 51 days, mean age 23 years, (SD 6.4) and eight hospital controls (mean age 29 years, (SD 5.9) were tested. No differences were found between the patients and controls in the effects of task load on performance and the amount of mental effort, even in very demanding simulated work conditions. This parallels previous findings in less demanding laboratory tasks of sustained attention. Effects of CHI were found on both subjective and physiological indicators of distress. Compared to the controls, patients showed stronger effects on systolic blood pressure and subjectively experienced load

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Hyperfeineigenschaften und Gitterrelaxationen von Defekten in Halbleitern und Metallen

The electronic and geometrical structures, in particular the electric field gradients (EFGs), of [CdD]$^{-}$ (D=P, As, Sb) acceptor-donor pairs in Si and Ge are studied using the full potential Korringa-Kohn-Rostoker (KKR) Green's function method. Since the EFG depends very sensitively an lattice relaxations, the method is extended to treat large displacements with higher accuracy and less computing time. The efficiency is demonstrated for impurities in semiconductors and metals. The hyperfine fields of 5$\textit{sp}$- und 6$\textit{sp}$-defects in Fe are also calculated. In the case of [InD]° the calculated geometrical structures are compared with pseudopotential results and are in quite good agreement. The EFGs for [CdD]$^{0/-}$ complexes and for the trimers [CdD$_{2}$] (D=P, As) in the relaxed positions agree well with experimental results. In all cases the origin of the EFGs can be qualitatively understood by simple hybridization models

Lattice relaxations and hyperfine fields of heavy impurities in Fe

We present first-principles calculations of the lattice relaxations and hyperfine fields of heavy impurities in bcc Fe. We consider impurities of the 5sp and 6sp series, containing the largest atoms in the periodic table. As an application we calculate the hyperfine fields of these impurities and in particular the effects of lattice relaxations on these fields. The calculations are based on a full-potential Korringa-Kohn-Rostoker Green's-function method for defects and employ the local spin-density approximation for the exchange and correlation effects. The nonspherical parts of the potential and the charge density are included in the calculations and the forces are calculated by an ionic version of the Hellmann-Feynman theorem. The resulting lattice relaxations are relatively small, even for the largest impurities considered. The comparison of the calculated hyperfine fields with the experimental data shows that the inclusion of lattice relaxations improves the overall agreement with experiment