Analysis of Formative and Evaluative Activities on Statistical Graphs in Textbooks for Chilean Rural Multigrade Education.

The aim of this paper is to analyze the formative and evaluative activities involving statistical graphs in the new textbooks for Chilean rural multigrade education. The methodology is qualitative, at a descriptive level and uses the content analysis technique. The sample is made up of the six primary education textbooks distributed by the Ministry of Education for rural multigrade schools. The results show the predominance of the bar chart, semiotic level 3, the task of calculating and the personal context in both types of activities, although with respect to the reading level, it is evident that level 4 predominates in the formative activities and level 2 in the evaluative ones. According to the results, it is recommended to incorporate graphs proposed by the curricular guidelines of the Ministry of Education, which are absent in textbooks as well as to include evaluative activities that require reflection on the nature of the data, context, representation and conclusions obtained from them.

Entire papilla preservation technique for treatment of periodontal intrabony defects: a series of cases.

OBJECTIVE: Periodontitis is characterized by bone resorption. Vertical bone loss results in an intraosseous defect. Multiple surgical approaches for treating intrabony defects have shown different grades of effectiveness. Recently, the entire papilla preservation technique has been proposed, improving clinical parameters, such as pocket depth and clinical attachment level. This series of cases aimed to describe the use of the entire papilla preservation surgical technique without using biomaterials to regenerate periodontal intrabony defects. The influence on the clinical periodontal parameters and radiographic parameters was measured through CBCT, the latter not described until now, and analyzed the possible postoperative complications. METHOD AND MATERIALS: A total of six intrabony periodontal defects associated with at least one periodontal pocket with probing depths equal to or greater than 6 mm were treated with the entire papilla preservation technique. The clinical and radiographic parameters were evaluated at the beginning and 6 months after surgery. RESULTS: The mean probing pocket depth reduction was 4.00 ± 0.63 mm, the mean clinical attachment level gain was 3.67 ± 1.03 mm, and the mean radiographic intrabony filling was 2.41 ± 2.03 mm. Early healing was uneventful; the mean visual analog scale at 7 days was 0. CONCLUSIONS: This minimally invasive technique results in an improvement in clinical and radiographic parameters, the latter showing a filling of the bone defect observed during the 6-month evaluation after surgical treatment. These results confirm the importance of clot and flap stability in regenerating intraosseous defects.

Modeling plant interspecific interactions from experiments with perennial crop mixtures to predict optimal combinations.

The contribution of plant species richness to productivity and ecosystem functioning is a longstanding issue in ecology, with relevant implications for both conservation and agriculture. Both experiments and quantitative modeling are fundamental to the design of sustainable agroecosystems and the optimization of crop production. We modeled communities of perennial crop mixtures by using a generalized Lotka-Volterra model, i.e., a model such that the interspecific interactions are more general than purely competitive. We estimated model parameters -carrying capacities and interaction coefficients- from, respectively, the observed biomass of monocultures and bicultures measured in a large diversity experiment of seven perennial forage species in Iowa, United States. The sign and absolute value of the interaction coefficients showed that the biological interactions between species pairs included amensalism, competition, and parasitism (asymmetric positive-negative interaction), with various degrees of intensity. We tested the model fit by simulating the combinations of more than two species and comparing them with the polycultures experimental data. Overall, theoretical predictions are in good agreement with the experiments. Using this model, we also simulated species combinations that were not sown. From all possible mixtures (sown and not sown) we identified which are the most productive species combinations. Our results demonstrate that a combination of experiments and modeling can contribute to the design of sustainable agricultural systems in general and to the optimization of crop production in particular.