Technology for noninvasive mechanical ventilation: looking into the black box

Current devices for providing noninvasive respiratory support contain sensors and built-in intelligence for automatically modifying ventilation according to the patient's needs. These devices, including automatic continuous positive airway pressure devices and noninvasive ventilators, are technologically complex and offer a considerable number of different modes of ventilation and setting options, the details of which are sometimes difficult to capture by the user. Therefore, better predicting and interpreting the actual performance of these ventilation devices in clinical application requires understanding their functioning principles and assessing their performance under well controlled bench test conditions with simulated patients. This concise review presents an updated perspective of the theoretical basis of intelligent continuous positive airway pressure and noninvasive ventilation devices, and of the tools available for assessing how these devices respond under specific ventilation phenotypes in patients requiring breathing support

Microstructural and mechanical properties analysis of extruded Sn–0.7Cu solder alloy

AbstractThe properties and performance of lead-free solder alloys such as fluidity and wettability are defined by the alloy composition and solidification microstructure. Rapid solidification of metallic alloys is known to result in refined microstructures with reduced microsegregation and improved mechanical properties of the final products as compared to normal castings. The rapidly solidified Sn-based solders by melt spinning were shown to be suitable for soldering with low temperature and short soldering duration. In the present study, rapidly solidified Sn–0.7wt.%Cu droplets generated by impulse atomization (IA) were achieved as well as directional solidification under transient conditions at lower cooling rate. This paper reports on a comparative study of the rapidly solidified and the directionally solidified samples. Different but complementary characterization techniques were used to fully analyze the solidification microstructures of the samples obtained under the two cooling regimes. These include X-ray diffractometry (XRD) and scanning electron microscopy (SEM). In order to compare the tensile strength and elongation to fracture of the directionally solidified ingot and strip castings with the atomized droplet, compaction and extrusion of the latter were carried out. It was shown that more balanced and superior tensile mechanical properties are available for the hot extruded samples from compacted as-atomized Sn–0.7wt.%Cu droplets. Further, elongation-to-fracture was 2–3× higher than that obtained for the directionally solidified samples

Un estudio de la covariación con profesores universitarios usando tecnología

En el presente estudio se analizaron las producciones de 13 profesores universitarios relacionadas con 4 enunciados verbales referidos a la rapidez de variación, antes y después de que desarrollaran actividades de laboratorio usando tecnología de calculadoras graficadoras y sensores de parámetros físicos diversos para obtener y analizar, gráficas cartesianas generadas en tiempo real, durante un curso de 30 horas. El objetivo de esta experiencia fue dotar a los docentes universitarios de elementos que les permitieran resignificar los contenidos asociados al análisis gráfico de funciones, en términos del cambio y la variación tomando en cuenta que, al estudiar diferentes fenómenos físicos, se confrontan relaciones entre los sentidos corporales y los sistemas de representación. Buscamos, bajo un acercamiento fenomenológico del cálculo, aproximarnos a las intuiciones y vivencias cotidianas de los participantes

A quantum genetic algorithm with quantum crossover and mutation operations

In the context of evolutionary quantum computing in the literal meaning, a quantum crossover operation has not been introduced so far. Here, we introduce a novel quantum genetic algorithm which has a quantum crossover procedure performing crossovers among all chromosomes in parallel for each generation. A complexity analysis shows that a quadratic speedup is achieved over its classical counterpart in the dominant factor of the run time to handle each generation.Comment: 21 pages, 1 table, v2: typos corrected, minor modifications in sections 3.5 and 4, v3: minor revision, title changed (original title: Semiclassical genetic algorithm with quantum crossover and mutation operations), v4: minor revision, v5: minor grammatical corrections, to appear in QI

El aprendizaje colaborativo en un curso de geometría analítica

Para Dillenbourg (1999), una característica del trabajo colaborativo es que las personas involucradas en él reflexionan en términos de su propia práctica; esto significa que poseen la habilidad de mirar en retrospectiva y ver lo que han hecho o lo que están haciendo, para criticarlo, para evaluar lo que parece ser relevante, y revisar lo que parece no serlo. Esta práctica reflexiva parece ser promovida por el ambiente del TI-Navigator, el cual permite a los estudiantes tomar distancia de sus propias producciones e incluirse a sí mismos más fácilmente en un intercambio entre sus pares. La presente propuesta considera el uso de una red inalámbrica de calculadoras en la realización de tres actividades generativas que promuevan el trabajo colaborativo durante la introducción a los temas de la elipse, la parábola y la hipérbola en un curso de geometría analítica de educación media superior

Oligomerization of amyloid Abeta peptides using hydrogen bonds and hydrophobicity forces

The 16-22 amino acid fragment of the beta-amyloid peptide associated with the Alzheimer's disease, Abeta, is capable of forming amyloid fibrils. Here we study the aggregation mechanism of Abeta(16-22) peptides by unbiased thermodynamic simulations at the atomic level for systems of one, three and six Abeta(16-22) peptides. We find that the isolated Abeta(16-22) peptide is mainly a random coil in the sense that both the alpha-helix and beta-strand contents are low, whereas the three- and six-chain systems form aggregated structures with a high beta-sheet content. Furthermore, in agreement with experiments on Abeta(16-22) fibrils, we find that large parallel beta-sheets are unlikely to form. For the six-chain system, the aggregated structures can have many different shapes, but certain particularly stable shapes can be identified.Comment: 19 pages, 7 figures (to appear in Biophys. J.

Sustainable Strategy Based on Induced Precipitation for the Purification of Phycobiliproteins

Phycobiliproteins are fluorescent proteins mainly produced by red macroalgae and cyanobacteria. These proteins, essential to the survival of these organisms, find application in many fields of interest, from medical, pharmaceutical, and cosmetic to food and textile industries. The biggest obstacle to their use is the lack of simple environmental and economical sustainable methodologies to obtain these proteins with high purity. In this work, a new purification process is proposed based on the induced precipitation of the target proteins followed by ultrafiltration. Purities of 89.5% of both phycobiliproteins and 87.3% of R-phycoerythrin were achieved using ammonium sulfate and poly(acrylic acid) sodium salts as precipitation agents (followed by an ultrafiltration step), while maintaining high recovery yields and protein structure stability. Environmental analysis performed to evaluate the proposed process shows that the carbon footprint for the proposed process is much lower than that reported for alternative methodology, and the economic analysis reveals the cost-effective character associated to its high performance. This work is a step toward more sustainable and effective methodologies/processes with high industrial potential