Propuesta didáctica para contribuir en la comprensión y uso de números fraccionarios a través de diferentes representaciones en secundaria

"Identificar los errores más frecuentes en el tema de las fracciones abre la posibilidad de contribuir a reducirlas. La comprensión de los números fraccionarios es una dificultad que presenta el alumno en diversos niveles educativos, es común que no comprenda sus diferentes representaciones ni pueda transformar una representación en otra (decimal, fracción, punto en una recta, gráfico, etc.). Tomando en cuenta que se requiere de representaciones para realizar cualquier actividad matemática (Duval, 2006 ; D´Amore, 2009) entonces el uso adecuado de las transformaciones semióticas puede favorecer la comprensión del significado del concepto de fracción, para esto, los estudiantes necesitan tiempo y una alternativa metodológica con la que puedan observar y trabajar en equipo sobre la construcción de la noción de fracción, independientemente del registro en el que se encuentren representados. Al aplicar una prueba de diagnóstico a un grupo de primer grado de secundaria se determinó que estos estudiantes presentaban varias de las dificultades mencionadas por Kieren (1976), De León y Fuenlabrada (1996), Perera y Valdemoros (2007), Fandiño (2009) y Block et al. (2010). Además, aproximadamente la mitad del total de los participantes presentó dificultades en la conversión de fracción a decimal. Cerca de la tercera parte 16 presentó dificultades en la conversión de decimal a fracción, y más de las tres cuartas partes del grupo participante falló al localizar y ubicar fracciones y decimales en la recta numérica. Dada esta problemática se consideró necesaria y oportuna una alternativa didáctica que contribuyera a precisar algunos aspectos del concepto de fracción a través de sus diferentes representaciones semióticas, por ejemplo: unidad, fracción de la unidad, fracción como división indicada, fracción como división efectuada, relación de orden entre fracciones, fracción con unidad de medida y manejo lingüístico de la fracción.

Determinación de las estrategias implementadas para prevención y/o intervención de consumo de tabaco, en jóvenes estudiantes de establecimientos educacionales de la Fundación Belén Educa, en la Región Metropolitana de Chile en el año 2015

Tesis (Licenciatura en Kinesiología)El objetivo de este estudio, es determinar el tipo de estrategias que están siendo implementadas para prevenir y/o intervenir el consumo temprano de tabaco, en los distintos establecimientos educacionales que pertenecen a la Fundación Belén Educa, ubicados en la Región Metropolitana de Chile. Para este fin, se creó una encuesta que permitió obtener la información necesaria en 10 de los 11 establecimientos de la FBE, con la cual se obtuvieron resultados relacionados a los enfoques teóricos aplicados en cada establecimiento (de carácter informativo, habilidades sociales e influencia social) y las estrategias utilizadas y conocidas por cada uno. De los resultados obtenidos se pudo observar que las estrategias más utilizadas son de carácter informativo, las cuales si bien son de fácil aplicación, son poco efectivas. Se pudo apreciar, que el conocimiento y aplicación de las estrategias por parte de los establecimientos es bastante desigual. Si bien, las estrategias que se utilizan en Chile, son muy similares a las usadas en los países con bajos índices de consumo de tabaco, esto no se ve reflejado en los niveles de consumo en jóvenes de nuestro país, que siguen siendo muy altos. En Chile se han creado estrategias y planes de acción para el consumo de tabaco en jóvenes, pero el principal problema es que no existe una continuidad y seguimiento sobre la aplicación de éstas. Esto último, impide que haya un registro claro y accesible sobre los resultados que se obtienen, al aplicar las estrategias que se están planteando

Semicontinuous and batch ozonation combined with peroxymonosulfate for inactivation of microalgae in ballast water.

The Ballast Water Management Convention (BWMC) establishes limits regarding the permissible number of viable organisms in discharged ballast water. Ozone as a ballast water treatment is interesting because it can be generated in-situ and has strong oxidant power. Additionally, some oxidants can be formed in reaction with seawater, especially brominated compounds, that assist in inactivating microorganisms. The objective of this study is to assess the efficacy of semicontinuous and batch ozonation as well as their combination with peroxymonosulfate salt (PMS) as methods to be used to ensure compliance with regulation D2 of the BWMC using Tetraselmis suecica as a standard microorganism. Growth modeling method was employed to determine the inactivation achieved by the treatments. The results show that ozone is an effective treatment for accomplishing the D2 of the BWMC. Batch ozonation is more efficient than semicontinuous ozonation probably because of the brominated compounds formed during the ozone saturation of the water. The oxidants that are developed during the ozonation of seawater prolong the residual effect of the treatment throughout the days of storage with practically no presence of them in the ballast tanks at 72 h. The addition of the PMS increases the inactivation in the semicontinuous ozonation, but a threshold concentration of ozone is needed to observe the synergistic effect of both oxidants. No increase is associated with the combination of O3 and PMS in the case of batch ozonation

El impacto de una intervención didáctica para la comprensión del concepto de fracción a través de representaciones semióticas en estudiantes de secundaria / The impact of a didactic intervention on the understanding of the concept of fraction through the semiotic representations on students of high school

Se muestran los resultados de una intervención didáctica basada en las transformaciones y conversiones de representaciones semióticas en alumnos de secundaria. Las actividades en las que se involucraron a los alumnos buscaron favorecer la construcción de algunos elementos del concepto de fracción. También se fomentó el uso de las fracciones en contextos familiares y variados y se indagó cuáles eran los errores más comunes en las diferentes representaciones utilizadas. Algunos resultados coinciden con lo ya reportado por otros autores. Por ejemplo, al utilizar y operar las fracciones los alumnos no lograron relacionar sus conocimientos previos con diferentes representaciones. También, el carácter multifacético del concepto originó dificultades de comprensión. En general, los resultados de la aplicación de la propuesta didáctica fueron favorables, se observaron diferentes índices de logros en las distintas transformaciones y conversiones manejadas

Using Interpretable Machine Learning to Identify Baseline Predictive Factors of Remission and Drug Durability in Crohn’s Disease Patients on Ustekinumab

Ustekinumab has shown efficacy in Crohn's Disease (CD) patients. To identify patient profiles of those who benefit the most from this treatment would help to position this drug in the therapeutic paradigm of CD and generate hypotheses for future trials. The objective of this analysis was to determine whether baseline patient characteristics are predictive of remission and the drug durability of ustekinumab, and whether its positioning with respect to prior use of biologics has a significant effect after correcting for disease severity and phenotype at baseline using interpretable machine learning. Patients' data from SUSTAIN, a retrospective multicenter single-arm cohort study, were used. Disease phenotype, baseline laboratory data, and prior treatment characteristics were documented. Clinical remission was defined as the Harvey Bradshaw Index <= 4 and was tracked longitudinally. Drug durability was defined as the time until a patient discontinued treatment. A total of 439 participants from 60 centers were included and a total of 20 baseline covariates considered. Less exposure to previous biologics had a positive effect on remission, even after controlling for baseline disease severity using a non-linear, additive, multivariable model. Additionally, age, body mass index, and fecal calprotectin at baseline were found to be statistically significant as independent negative risk factors for both remission and drug survival, with further risk factors identified for remission

Long-Term Real-World Effectiveness and Safety of Ustekinumab in Crohn’s Disease Patients: The SUSTAIN Study

Background Large real-world-evidence studies are required to confirm the durability of response, effectiveness, and safety of ustekinumab in Crohn’s disease (CD) patients in real-world clinical practice. Methods A retrospective, multicentre study was conducted in Spain in patients with active CD who had received ≥1 intravenous dose of ustekinumab for ≥6 months. Primary outcome was ustekinumab retention rate; secondary outcomes were to identify predictive factors for drug retention, short-term remission (week 16), loss of response and predictive factors for short-term efficacy and loss of response, and ustekinumab safety. Results A total of 463 patients were included. Mean baseline Harvey-Bradshaw Index was 8.4. A total of 447 (96.5%) patients had received prior biologic therapy, 141 (30.5%) of whom had received ≥3 agents. In addition, 35.2% received concomitant immunosuppressants, and 47.1% had ≥1 abdominal surgery. At week 16, 56% had remission, 70% had response, and 26.1% required dose escalation or intensification; of these, 24.8% did not subsequently reduce dose. After a median follow-up of 15 months, 356 (77%) patients continued treatment. The incidence rate of ustekinumab discontinuation was 18% per patient-year of follow-up. Previous intestinal surgery and concomitant steroid treatment were associated with higher risk of ustekinumab discontinuation, while a maintenance schedule every 12 weeks had a lower risk; neither concomitant immunosuppressants nor the number of previous biologics were associated with ustekinumab discontinuation risk. Fifty adverse events were reported in 39 (8.4%) patients; 4 of them were severe (2 infections, 1 malignancy, and 1 fever). Conclusions Ustekinumab is effective and safe as short- and long-term treatment in a refractory cohort of CD patients in real-world clinical practice

Immigrant IBD Patients in Spain Are Younger, Have More Extraintestinal Manifestations and Use More Biologics Than Native Patients

BackgroundPrevious studies comparing immigrant ethnic groups and native patients with IBD have yielded clinical and phenotypic differences. To date, no study has focused on the immigrant IBD population in Spain. MethodsProspective, observational, multicenter study comparing cohorts of IBD patients from ENEIDA-registry who were born outside Spain with a cohort of native patients. ResultsWe included 13,524 patients (1,864 immigrant and 11,660 native). The immigrants were younger (45 +/- 12 vs. 54 +/- 16 years, p < 0.001), had been diagnosed younger (31 +/- 12 vs. 36 +/- 15 years, p < 0.001), and had a shorter disease duration (14 +/- 7 vs. 18 +/- 8 years, p < 0.001) than native patients. Family history of IBD (9 vs. 14%, p < 0.001) and smoking (30 vs. 40%, p < 0.001) were more frequent among native patients. The most prevalent ethnic groups among immigrants were Caucasian (41.5%), followed by Latin American (30.8%), Arab (18.3%), and Asian (6.7%). Extraintestinal manifestations, mainly musculoskeletal affections, were more frequent in immigrants (19 vs. 11%, p < 0.001). Use of biologics, mainly anti-TNF, was greater in immigrants (36 vs. 29%, p < 0.001). The risk of having extraintestinal manifestations [OR: 2.23 (1.92-2.58, p < 0.001)] and using biologics [OR: 1.13 (1.0-1.26, p = 0.042)] was independently associated with immigrant status in the multivariate analyses. ConclusionsCompared with native-born patients, first-generation-immigrant IBD patients in Spain were younger at disease onset and showed an increased risk of having extraintestinal manifestations and using biologics. Our study suggests a featured phenotype of immigrant IBD patients in Spain, and constitutes a new landmark in the epidemiological characterization of immigrant IBD populations in Southern Europe

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