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In patients with hypoxemic acute respiratory failure (ARF), randomized studies have shown noninvasive positive pressure ventilation (NPPV) to be associated with lower rates of endotracheal intubation. In these patients, predictors of NPPV failure are not well characterized. To investigate variables predictive of NPPV failure in patients with hypoxemic ARF. Prospective, multicenter cohort study. Eight Intensive Care Units (ICU) in Europe and USA. Of 5,847 patients admitted between October 1996 and December 1998, 2,770 met criteria for hypoxemic ARF. Of these, 2,416 were already intubated and 354 were eligible for the study. NPPV failed in 30% (108/354) of patients. The highest intubation rate was observed in patients with ARDS (51%) or community-acquired pneumonia (50%). The lowest intubation rate was observed in patients with cardiogenic pulmonary edema (10%) and pulmonary contusion (18%). Multivariate analysis identified age > 40 years (OR 1.72, 95% CI 0.92-3.23), a simplified acute physiologic score (SAPS II) > or = 35 (OR 1.81, 95% CI 1.07-3.06), the presence of ARDS or community-acquired pneumonia (OR 3.75, 95% CI 2.25-6.24), and a PaO2:FiO2 < or = 146 after 1 h of NPPV (OR 2.51, 95% CI 1.45-4.35) as factors independently associated with failure of NPPV. Patients requiring intubation had a longer duration of ICU stay ( P < 0.001), higher rates of ventilator-associated pneumonia and septic complications ( P < 0.001), and a higher ICU mortality ( P < 0.001). In hypoxemic ARF, NPPV can be successful in selected populations. When patients have a higher severity score, an older age, ARDS or pneumonia, or fail to improve after 1 h of treatment, the risk of failure is higher.

Purpose The use of non-invasive ventilation (NIV) in severe acute respiratory failure (ARF) due to community-acquired pneumonia (CAP) is controversial, and the risk factors for NIV failure in these patients are not well known. We assessed the characteristics and predictors of outcome of patients with CAP and severe ARF treated with NIV. Methods We prospectively assessed 184 consecutive patients; 102 had “de novo” ARF, and 82 previous cardiac or respiratory disease. We defined successful NIV as avoidance of intubation and intensive care unit (ICU) survival at least 24 h in the ward. We assessed predictors of NIV failure and hospital mortality in multivariate analyses. Results Patients with “de novo” ARF failed NIV more frequently than patients with previous cardiac or respiratory disease (47, 46% versus 21, 26%, p  = 0.007). Worsening radiologic infiltrate 24 h after admission, maximum Sepsis-Related Organ Failure Assessment (SOFA) score and, after 1 h of NIV, higher heart rate and lower PaO 2 /FiO 2 and bicarbonate independently predicted NIV failure. Likewise, maximum SOFA, NIV failure and older age independently predicted hospital mortality. Among intubated patients with “de novo” ARF, NIV duration was shorter in hospital survivors than non-survivors (32 ± 24 versus 78 ± 65 h, p  = 0.014). In this group, longer duration of NIV before intubation was associated with decreased hospital survival (adjusted odds ratio 0.978, 95% confidence interval 0.962–0.995, p  = 0.012). This association was not observed in patients with previous cardiac or respiratory disease. Conclusions Successful NIV was strongly associated with better survival. If predictors for NIV failure are present, avoiding delayed intubation of patients with “de novo” ARF would potentially minimise mortality.

With the purpose to compare the physical features of the electromagnetic field, we describe the synthesis of optical singularities propagating in the free space and on a metal surface. In both cases the electromagnetic field has a slit-shaped curve as a boundary condition, and the singularities correspond to a shock wave that is a consequence of the curvature of the slit curve. As prototypes, we generate singularities that correspond to fold and cusped regions. We show that singularities in free space may generate bifurcation effects while plasmon fields do not generate these kinds of effects. Experimental results for free-space propagation are presented and for surface plasmon fields, computer simulations are shown.

Background Non-invasive mechanical ventilation (NIV) in patients with acute respiratory failure has been traditionally determined based on clinical assessment and changes in blood gases, with NIV support pressures manually adjusted by an operator. Bilevel positive airway pressure-spontaneous/timed (BiPAP S/T) with average volume assured pressure support (AVAPS) uses a fixed tidal volume that automatically adjusts to a patient’s needs. Our study assessed the use of BiPAP S/T with AVAPS in patients with chronic obstructive pulmonary disease (COPD) and hypercapnic encephalopathy as compared to BiPAP S/T alone, upon immediate arrival in the Emergency-ICU. Methods We carried out a prospective interventional match-controlled study in Guayaquil, Ecuador. A total of 22 patients were analyzed. Eleven with COPD exacerbations and hypercapnic encephalopathy with a Glasgow Coma Scale (GCS) <10 and a pH of 7.25-7.35 were assigned to receive NIV via BiPAP S/T with AVAPS. Eleven patients were selected as paired controls for the initial group by physicians who were unfamiliar with our study, and these patients were administered BiPAP S/T. Arterial blood gases, GCS, vital signs, and ventilatory parameters were then measured and compared between the two groups. Results We observed statistically significant differences in favor of the BiPAP S/T + AVAPS group in GCS ( P = .00001), pCO 2 ( P = .03) and maximum inspiratory positive airway pressure (IPAP) ( P = .005), among others. However, no significant differences in terms of length of stay or days on NIV were observed. Conclusions BiPAP S/T with AVAPS facilitates rapid recovery of consciousness when compared to traditional BiPAP S/T in patients with chronic obstructive pulmonary disease and hypercapnic encephalopathy. Trial registration Current Controlled Trials application ref is ISRCTN05135218

Intermediate-band semiconductors have attracted much attention for use in silicon-based solar cells and infrared detectors. In this work, n-Si substrates have been implanted with very high doses (1013 cm−2 and 1014 cm−2) of vanadium, which gives rise to a supersaturated layer inside the semiconductor. However, the Mott limit was not exceeded. The energy levels created in the supersaturated silicon were studied in detail by means of thermal admittance spectroscopy. We found a single deep center at energy near EC − 200 meV. This value agrees with one of the levels found for vanadium in silicon. The capture cross-section values of the deep levels were also calculated, and we found a relationship between the capture cross-section and the energy position of the deep levels which follows the Meyer–Neldel rule. This process usually appears in processes involving multiple excitations. The Meyer–Neldel energy values agree with those previously obtained for silicon supersaturated with titanium and for silicon contaminated with iron.

Purpose Antimalarial drug resistance is a global public health problem that leads to treatment failure. Synergistic drug combinations can improve treatment outcomes and delay the development of drug resistance. Here, we describe the implementation of a freely available computational tool, Machine Learning Synergy Predictor (MLSyPred©), to predict potential synergy in antimalarial drug combinations. Methods The MLSyPred© synergy prediction method extracts molecular fingerprints from the drugs’ biochemical structures to use as features and also cleans and prepares the raw data. Five machine learning algorithms (Logistic Regression, Random Forest, Support vector machine, Ada Boost, and Gradient Boost) were implemented to build prediction models. Implementation and application of the MLSyPred© tool were tested using datasets from 1540 combinations of 79 drugs and compounds biologically evaluated in pairs for three strains of Plasmodium falciparum (3D7, HB3, and Dd2). Results The best prediction models were obtained using Logistic Regression for antimalarials with the strains Dd2 and HB3 (0.81 and 0.70 AUC, respectively) and Random Forest for antimalarials with 3D7 (0.69 AUC). The MLSyPred© tool yielded 45% precision for synergistically predicted antimalarial drug combinations that were annotated and biologically validated, thus confirming the functionality and applicability of the tool. Conclusion  The MLSyPred© tool is freely available and represents a promising strategy for discovering potential synergistic drug combinations for further development as novel antimalarial therapies.

The evaluation of mathematical functions is a critical task in several hardware designs, and piecewise polynomial approximation (PPA) is one of the main techniques widely used for function evaluation. This technique employs uniform and non-uniform segmentation for splitting the function and approaching each function segment via polynomial approximation, where lookup tables are needed to store the polynomial coefficients. Today, several hardware-based PPA implementations have address decoder units with a considerable amount of hardware complexity. To face this problem, this paper proposes a new methodology that searches the optimal function segments, polynomial coefficients, and their representation in fixed-point format when the design is constrained to a decoder word-length. Thus, a second-order PPA evaluation architecture based on the Horner’s rule and a simplified address decoder unit with reduced complexity are provided. The proposed methodology uses non-uniform segmentation relying on a linear combination of power-of-two, which results in a reduction of the number of segments and consequently in the hardware complexity of the address decoder unit. The figures of merit employed by the auto-tuning (self-adapting) segmentation process are the first-order derivative (slope) of the function and the signal to quantization noise ratio quality signal metric. Experimental results show a hardware reduction of the decoder design (number of segments, polynomial coefficient ROMs) when is compared with state-of-the-art proposals.

We present results derived from continuous and localized 35 keV ⁵⁵Mn⁺ ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature.

Nowadays more reports in the use of tunable lenses are reported, it is due to the benefits they offer in optical systems design. A tunable lens is an optical system that can focus on a range of positions by changing dynamically one of its geometric parameters. There are several types of tunable lenses, the most known types are the liquid, the solid elastic, with variable refractive index, and lenses that use a dielectric medium. This paper presents the analysis and opto-mechanical design of two tunable lenses, a liquid lens and another Solid Elastic Lens (SEL). Both lenses are made in mounting aluminium and polydimethylsiloxane (PDMS) as refractor medium, the liquid lens use two elastic membranes containing a liquid medium between them while the SEL only use PDMS material as body of the lens (medium refractor). We describe the opto-mechanical performance of both types of lens highlighting the main features of each. Finally, results of a opto-functional comparison between these prototypes are showed.