Análisis de las propiedades mecánicas de tenacidad, esfuerzo de tensión y dureza de la aleación de aluminio 2024 t4, tratado térmicamente mediante el endurecimiento por precipitación a 180 °c

La aleación de aluminio 2024 T4 es una aleación de la serie 2XXX, que tiene cobre como principal elemento aleante, el cual favorece de manera notable la resistencia a la tracción y la dureza, convirtiéndolo en un material útil para la industria e ingeniería; es ampliamente utilizada en la industria aeronáutica, ya que estas aleaciones son ligeras y resistentes a la vez, lo cual proporciona una disminución en el peso de la aeronave, lo que implica un menor consumo de combustible y un aumento de velocidad. Por lo generar la aleación de aluminio 2024 T4 es empleada en la fabricación del fuselaje de las aeronaves, recubrimiento de las alas y de la fabricación de elementos de fijación como remaches, tornillos, pernos y tuercas. Para aumentar las propiedades mecánicas (tenacidad, esfuerzo de tensión y dureza) y microestructurales de las aleaciones de aluminio, se procede en la mayoría de los casos a implementar un tratamiento térmico de endurecimiento por precipitación (tratamiento térmico de envejecido), en el cual los elementos de la aleación deben ser parcialmente solubles en estado sólido con el aluminio Respecto al endurecimiento por precipitación de la aleación de aluminio 2024 T4 se han desarrollado diversos estudios, entre los cuales es de resaltar: La investigación de NAIDU GURUGUGELLI, Swami. (2012). "The Effect of Ageing on Impact Toughness and Microstructure of 2024 Al-Cu-Mg Alloy". En la cual se estudio el efecto del endurecimiento por precipitación en las propiedades mecánicas (tenacidad y dureza) y la microestructura en la aleación de aluminio 2024, con una temperatura de precipitación de 200 °C y tiempos de sostenimiento entre 1 y 18 horas. En esta investigación se observa que la dureza aumenta en las primeras horas de sostenimiento hasta obtener su máximo de 162 HV a las 10 horas y a partir de este tiempo comienza a disminuir gradualmente debido a la aparición de precipitados de fases intermedias de mayor tamaño. Además se concluye que la tenacidad depende en un gran porcentaje a las variables microestructurales y son afectadas, por factores como la resistencia a la fluencia, ductilidad y la temperatura, además se identifica que la muestra con mayor dureza tiene la tenacidad más baj

Cultural Differences between University Students in Online Learning Quality and Psychological Profile during COVID-19

During the COVID-19 pandemic, educational systems had to adapt to the social and health situation immediately. This led to the appearance of the asynchronous teaching model. Throughout the pandemic at an educational level, we can distinguish three phases, eminently online, hybrid, and face-to-face. However, the perception of educational quality in these three educational moments, considering the psychometric profile and cultural differences comparing Ibero-American countries, has not been studied. The study aims to analyze the psychological profile, and perception of quality in the teaching–learning processes at the university stage, during the three processes of educational transition during COVID-19: online, hybrid, and face-to-face. Thus, 1093 university students from Ibero-American countries were studied. Through a questionnaire, demographic, academic, and psychological variables were analyzed during three phases of the pandemic. Data suggest that Latin American students had higher levels of trait anxiety and stress perception, as well as higher levels of loneliness, during the online teaching phase (lockdown), but higher grades and higher levels of motivation compared to Europeans. Indeed, Latin Americans showed greater convenience, and preference for online learning methods. However, during the face-to-face teaching phase, European students presented greater motivation and grades, showing a greater preference for this method of learning than Latin American students. Factors such as resilience, a more unfavorable and pronounced pandemic evolution, and greater social inequities, may explain the present results. Furthermore, the present study suggests that despite the effect of the pandemic on mental health, online education is postulated as an effective teaching–learning alternative. Indeed, online teaching models have come to stay, not as a substitute, but as a tool, an essential focus of attention on these models should be conducted in European countries, while the governments of Latin American countries ensure that the infrastructures and resources are equitable to be able to correctly implement this teaching model

Gender Differences of University Students in the Online Teaching Quality and Psychological Profile during the COVID-19 Pandemic

With the arrival of COVID-19, educational systems have had to adapt to the social and health situation immediately. This led to the appearance of the asynchronous teaching model. Throughout the pandemic, at the educational level, we can distinguish three phases, eminently online, hybrid, and finally, face-to-face. However, the perception of educational quality in these three educational moments, taking into account the psychometric profile and gender, has not been studied. Thus, 1093 university students from Ibero-American countries were analyzed. Through a questionnaire, demographic, academic, and psychological variables were analyzed at three moments during the evolution of the pandemic. Data suggest that, during the lockdown phase, while teaching was eminently online, students presented higher levels of stress and higher difficulty of learning; class attendance, convenience, preferred method of learning, grading score, and motivation were lower, compared to other phases of teaching (hybrid and face-to-face). During this period, females presented higher stress levels than males, as well as higher levels of anxiety and loneliness, without gender differences among the other studied variables. During the hybrid and face-to-face phases, male students presented higher values in the results of difficulty learning and demanding activities. No differences were seen regarding motivation, synchronous class attendance, learning level, grades, convenience, or preferred learning method. The results from the present study suggest that, despite the effect of the pandemic on mental health, asynchronous education is postulated as an effective teaching–learning alternative. Yet, a special focus should be given to female students

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

Role of age and comorbidities in mortality of patients with infective endocarditis

[Purpose]: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. [Methods]: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015.Patients were stratified into three age groups:<65 years,65 to 80 years,and ≥ 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. [Results]: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 ≥ 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients ≥80 years who underwent surgery were significantly lower compared with other age groups (14.3%,65 years; 20.5%,65-79 years; 31.3%,≥80 years). In-hospital mortality was lower in the <65-year group (20.3%,<65 years;30.1%,65-79 years;34.7%,≥80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%,≥80 years; p = 0.003).Independent predictors of mortality were age ≥ 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI ≥ 3 (HR:1.62; 95% CI:1.39–1.88),and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared,the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. [Conclusion]: There were no differences in the clinical presentation of IE between the groups. Age ≥ 80 years, high comorbidity (measured by CCI),and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Spatiotemporal Characteristics of the Largest HIV-1 CRF02_AG Outbreak in Spain: Evidence for Onward Transmissions

Background and Aim: The circulating recombinant form 02_AG (CRF02_AG) is the predominant clade among the human immunodeficiency virus type-1 (HIV-1) non-Bs with a prevalence of 5.97% (95% Confidence Interval-CI: 5.41–6.57%) across Spain. Our aim was to estimate the levels of regional clustering for CRF02_AG and the spatiotemporal characteristics of the largest CRF02_AG subepidemic in Spain.Methods: We studied 396 CRF02_AG sequences obtained from HIV-1 diagnosed patients during 2000–2014 from 10 autonomous communities of Spain. Phylogenetic analysis was performed on the 391 CRF02_AG sequences along with all globally sampled CRF02_AG sequences (N = 3,302) as references. Phylodynamic and phylogeographic analysis was performed to the largest CRF02_AG monophyletic cluster by a Bayesian method in BEAST v1.8.0 and by reconstructing ancestral states using the criterion of parsimony in Mesquite v3.4, respectively.Results: The HIV-1 CRF02_AG prevalence differed across Spanish autonomous communities we sampled from (p &lt; 0.001). Phylogenetic analysis revealed that 52.7% of the CRF02_AG sequences formed 56 monophyletic clusters, with a range of 2–79 sequences. The CRF02_AG regional dispersal differed across Spain (p = 0.003), as suggested by monophyletic clustering. For the largest monophyletic cluster (subepidemic) (N = 79), 49.4% of the clustered sequences originated from Madrid, while most sequences (51.9%) had been obtained from men having sex with men (MSM). Molecular clock analysis suggested that the origin (tMRCA) of the CRF02_AG subepidemic was in 2002 (median estimate; 95% Highest Posterior Density-HPD interval: 1999–2004). Additionally, we found significant clustering within the CRF02_AG subepidemic according to the ethnic origin.Conclusion: CRF02_AG has been introduced as a result of multiple introductions in Spain, following regional dispersal in several cases. We showed that CRF02_AG transmissions were mostly due to regional dispersal in Spain. The hot-spot for the largest CRF02_AG regional subepidemic in Spain was in Madrid associated with MSM transmission risk group. The existence of subepidemics suggest that several spillovers occurred from Madrid to other areas. CRF02_AG sequences from Hispanics were clustered in a separate subclade suggesting no linkage between the local and Hispanic subepidemics

Psychological Impacts of Teaching Models on Ibero-American Educators during COVID-19

Educational systems globally, and notably in the Ibero-American context, underwent significant adaptations in response to the myriad challenges imposed by the COVID-19 pandemic. The pedagogical evolution unfolded through three discernible phases: predominantly online, hybrid, and ultimately, a return to face-to-face instruction. While these phases were universally apparent, cultural, socio-economic, and health disparities across regions subtly influenced the quality and experiential aspects of teaching and learning within these models. This study seeks to illuminate the psychological profiles and evaluative perspectives regarding teaching and learning quality among university educators during COVID-19’s tri-phase educational transformation. Engaging 601 university instructors from various Ibero-American countries, a comprehensive questionnaire mapped demographic, academic, and psychological landscapes across the pandemic’s distinctive epochs. The pivot to online educational methodologies, supplanting traditional modalities, permeated numerous facets of the educational endeavor, particularly impacting faculty life and wellbeing. Data underscored a prevalent sentiment of loneliness, indicative of broader mental health challenges, especially pronounced among educators in Latin American nations. Notwithstanding these hurdles, Latin American educators demonstrated a predilection towards online instruction, in stark contrast to their European peers, who exhibited a preference for in-person pedagogy. This study unveils the divergent pedagogical preferences and mental health challenges among university educators in the Ibero-American realm during COVID-19’s educational shifts, underlining the need for adaptable educational frameworks and robust mental health support, attuned to the region’s distinct socio-cultural and economic contexts.Revisión por pare

Adaptación del Máster en Desarrollo de Aplicaciones y Servicios Web a las nuevas necesidades de formación (4021)

El presente trabajo tiene como objetivo realizar un estudio sobre la conveniencia y viabilidad de adecuar la organización docente del Máster en Desarrollo de Aplicaciones y Servicios Web para el curso 2018/19. Esto viene fundamentado por el trabajo realizado durante los cursos anteriores y evaluación de indicadores obtenidos dentro del proceso de revisión, análisis y mejora del Sistema de Garantía Interna de Calidad del Máster. Dentro de este estudio se han realizado encuestas a estudiantes, se han analizado experiencias de másteres similares que han pasado a modalidad semipresencial, y finalmente se ha elaborado una propuesta de planificación de organización de las asignaturas del máster. En la red se cuenta con todo el profesorado a tiempo completo de la titulación. La documentación elaborada queda a disposición de la Comisión Académica de Máster para ser utilizada en los procesos de seguimiento de la titulación

Oral versus intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency: a pragmatic, randomised, multicentre, non-inferiority clinical trial undertaken in the primary healthcare setting (Project OB12)

Abstract Background The oral administration of vitamin B12 offers a potentially simpler and cheaper alternative to parenteral administration, but its effectiveness has not been definitively demonstrated. The following protocol was designed to compare the effectiveness of orally and intramuscularly administered vitamin B12 in the treatment of patients ≥65 years of age with vitamin B12 deficiency. Methods/design The proposed study involves a controlled, randomised, multicentre, parallel, non-inferiority clinical trial lasting one year, involving 23 primary healthcare centres in the Madrid region (Spain), and patients ≥65 years of age. The minimum number of patients required for the study was calculated as 320 (160 in each arm). Bearing in mind an estimated 8-10% prevalence of vitamin B12 deficiency among the population of this age group, an initial sample of 3556 patients will need to be recruited. Eligible patients will be randomly assigned to one of the two treatment arms. In the intramuscular treatment arm, vitamin B12 will be administered as follows: 1 mg on alternate days in weeks 1 and 2, 1 mg/week in weeks 3–8,and 1 mg/month in weeks 9–52. In the oral arm, the vitamin will be administered as: 1 mg/day in weeks 1–8 and 1 mg/week in weeks 9–52. The main outcome variable to be monitored in both treatment arms is the normalisation of the serum vitamin B12 concentration at weeks 8, 26 and 52; the secondary outcome variables include the serum concentration of vitamin B12 (in pg/ml), adherence to treatment, quality of life (EuroQoL-5D questionnaire), patient 3satisfaction and patient preferences. All statistical tests will be performed with intention to treat and per protocol. Logistic regression with random effects will be used to adjust for prognostic factors. Confounding factors or factors that might alter the effect recorded will be taken into account in analyses. Discussion The results of this study should help establish, taking quality of life into account, whether the oral administration of vitamin B12 is an effective alternative to its intramuscular administration. If this administration route is effective, it should provide a cheaper means of treating vitamin B12 deficiency while inducing fewer adverse effects. Having such an alternative would also allow patient preferences to be taken into consideration at the time of prescribing treatment. Trial registration This trial has been registered with ClinicalTrials.gov, number NCT 01476007, and under EUDRACT number 2010-024129-20.</p