Compact SAW aerosol generator

In this work, we discuss and demonstrate the principle features of surface acoustic wave (SAW) aerosol generation, based on the properties of the fluid supply, the acoustic wave field and the acoustowetting phenomena. Furthermore, we demonstrate a compact SAW-based aerosol generator amenable to mass production fabricated using simple techniques including photolithography, computerized numerical control (CNC) milling and printed circuit board (PCB) manufacturing. Using this device, we present comprehensive experimental results exploring the complexity of the acoustic atomization process and the influence of fluid supply position and geometry, SAW power and fluid flow rate on the device functionality. These factors in turn influence the droplet size distribution, measured here, that is important for applications including liquid chromatography, pulmonary therapies, thin film deposition and olfactory displays

La competencia "aprender a aprender" en un contexto educativo de ingeniería

The objective of this thesis was to establish bases to characterize "learn to learn" competence and to promote it in an engineering educational context. It adopted the vision of educational psychology that establishes self-regulation in learning as the operative manifestation of this competence. The research was developed in three phases: obtaining a psychometric tool to characterize self-regulation in learning; the characterization of self-regulation in learning of the students; and, based on the results of the characterization, an educational intervention was designed, implemented and evaluated to facilitate that students use the learning strategy of selection and organization of the information . In the first phase in order to obtain the psychometric tool was translated, adapted and validated the Motivated Strategies for Learning Questionnaire - MSLQ following the guidelines of the International Test Commission (ITC). The result was the MSLQ-Colombia. With the participation of 1218 students and 12 engineering professors, the psychometric properties of MSLQ-Colombia were studied: construct validity, content validity, external validity and reliability; the MSLQ-Colombia was valid and reliable. In the characterization, second phase, the self-regulation of the motivation and the use of learning strategies of 1268 students were evaluated. It was found that students self-regulate their motivation highly: beliefs about learning control and task value were the aspects most self-regulated, while the learning orientation toward extrinsic goals and anxiety in the assessment were the least self-regulated. It was found that students used learning strategies in a non-uniform way, there were strategies frequently used and others occasionally used. The three strategies most used were the monitoring of learning, control of the place of study and effort regulation; the strategies least used were time management and selection and organization of information. The results of this phase also allowed to propose a new hypothesis to investigate the self-regulation in the learning: the self-regulation of some aspects of the motivation and the use of some strategies depend on the subject that the students are coursing; on the contrary, other aspects of motivation and other learning strategies do not depend on the subject. Educational intervention, the third phase, consisted in offering instruction at students on summarizing technique to facilitate them to select and organize the information of engineering technical texts; in addition, students practiced the production of abstracts and the teachers provided them feedback on the quality of these abstracts. The effects of the educational intervention were explored with a quasi-experimental investigation (experimental group: 177 students, control group: 65 students) that collected quantitative and qualitative evidences. The educational intervention facilitated that students increase positive and significantly, in a statistical sense, the writing of abstracts to select and organize the information; the quality of the abstracts also significantly improved. The intervention also impacted the use of strategies such as metacognition and resource management as time management. The results of this thesis provide solutions to the current problems of the "learn to learn" competence: practical contributions such as the MSLQ-Colombia and the didactic sequence of the educational intervention, empirical contributions such as the psychometric indexes of MSLQ-Colombia, the characterization of the self-regulation in learning of students and the impacts of educational intervention. Finally, this thesis sets a new integrative approach (hypothesis) of the previous ones about the research on the self-regulation in learning.El objetivo de esta Tesis fue establecer bases para caracterizar la competencia "aprender a aprender" y potenciarla en un contexto educativo de ingeniería. Se adoptó la visión de la psicología educativa que instaura la autorregulación en el aprendizaje como la manifestación operativa de esta competencia. La investigación se desarrolló en tres fases: obtención de una herramienta psicométrica para caracterizar la autorregulación en el aprendizaje; caracterización de la autorregulación en el aprendizaje de los estudiantes; y, a partir de los resultados de la caracterización, se diseñó, implementó y evaluó una intervención educativa para facilitar a los estudiantes usar la estrategia de aprendizaje selección y organización de la información. En la primera fase para obtener la herramienta psicométrica se tradujo, adaptó y validó el Motivated Strategies for Learning Questionnaire - MSLQ siguiendo las directrices de la International Test Commission (ITC). El resultado fue el MSLQ-Colombia. Con la participación de 1218 estudiantes y 12 profesores de ingeniería se estudiaron las propiedades psicométricas del MSLQ-Colombia: validez de constructo, validez de contenido, validez externa y confiabilidad; el MSLQ-Colombia resultó válido y confiable. En la caracterización, segunda fase, se valoró la autorregulación de la motivación y el uso de estrategias de aprendizaje de 1268 estudiantes. Se encontró que los estudiantes autorregulaban altamente su motivación: las creencias de control del aprendizaje y la valoración de la tarea fueron los aspectos que más autorregularon, mientras que la orientación del aprendizaje hacia metas extrínsecas y la ansiedad en la evaluación fueron los menos autorregulados. Se halló que los estudiantes usaban estrategias de aprendizaje de manera no uniforme, hubo estrategias de uso frecuente y otras de uso ocasional. Las tres estrategias más usadas fueron el monitoreo del aprendizaje, control del lugar de estudio y regulación del esfuerzo; las menos usadas fueron la gestión del tiempo y selección y organización de la información. Los resultados de esta fase también permitieron plantear una nueva hipótesis para investigar la autorregulación en el aprendizaje: la autorregulación de algunos aspectos de la motivación y el uso de algunas estrategias dependen de la asignatura que los estudiantes están cursando; por el contrario, otros aspectos de la motivación y otras estrategias de aprendizaje no dependen de la asignatura. La intervención educativa, tercera fase, consistió en ofrecer a los estudiantes instrucción sobre la técnica de resumir para facilitarles seleccionar y organizar la información de textos técnicos de ingeniería; asimismo, los estudiantes elaboraron resúmenes y se les brindó realimentación sobre la calidad de dichos resúmenes. Los efectos de la intervención educativa se exploraron con una investigación cuasi-experimental (grupo experimental: 177 estudiantes, grupo control: 65 estudiantes) que recolectó evidencias cuantitativas y cualitativas. La intervención educativa facilitó que los estudiantes incrementaran positiva y significativamente, en sentido estadístico, la escritura de resúmenes para seleccionar y organizar la información; los estudiantes también mejoraron significativamente la calidad de los resúmenes. La intervención también impactó el uso de estrategias como la metacognición y la administración de recursos como gestión del tiempo. Los resultados de esta Tesis aportan soluciones a las problemáticas actuales de la competencia "aprender a aprender": contribuciones prácticas como el MSLQ-Colombia y la secuencia didáctica de la intervención educativa; contribuciones empíricas como los índices psicométricos del MSLQ-Colombia, la caracterización de la autorregulación del aprendizaje de los estudiantes y los impactos de la intervención educativa. Por último, esta Tesis establece un nuevo enfoque (hipótesis) integrador de los anteriores en la investigación de la autorregulación del aprendizaje

Integrated sensitive on-chip ion field effect transistors based on wrinkled InGaAs nanomembranes

Self-organized wrinkling of pre-strained nanomembranes into nanochannels is used to fabricate a fully integrated nanofluidic device for the development of ion field effect transistors (IFETs). Constrained by the structure and shape of the membrane, the deterministic wrinkling process leads to a versatile variation of channel types such as straight two-way channels, three-way branched channels, or even four-way intersection channels. The fabrication of straight channels is well controllable and offers the opportunity to integrate multiple IFET devices into a single chip. Thus, several IFETs are fabricated on a single chip using a III-V semiconductor substrate to control the ion separation and to measure the ion current of a diluted potassium chloride electrolyte solution

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - An observational study in 29 countries

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (V T) size was 500 ml, or 7 to 9 ml kg−1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P ˂ 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P ˂ 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high V T and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.</p

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND: One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES: The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING: This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES: Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS: This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P &lt; 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P &lt; 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION: In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov, NCT01601223