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A simple analytical model for a fast 3D assessment of peripheral photon dose during coplanar isocentric photon radiotherapy
(2022) Sánchez Nieto, Beatriz; López Martínez, Ignacio N.; Rodríguez Mongua, José Luis; Espinoza Bornscheuer, Ignacio Guillermo
Considering that cancer survival rates have been growing and that nearly two-thirds of those survivors were exposed to clinical radiation during its treatment, the study of long-term radiation effects, especially secondary cancer induction, has become increasingly important. To correctly assess this risk, knowing the dose to out-of-field organs is essential. As it has been reported, commercial treatment planning systems do not accurately calculate the dose far away from the border of the field; analytical dose estimation models may help this purpose. In this work, the development and validation of a new three-dimensional (3D) analytical model to assess the photon peripheral dose during radiotherapy is presented. It needs only two treatment-specific input parameter values, plus information about the linac-specific leakage, when available. It is easy to use and generates 3D whole-body dose distributions and, particularly, the dose to out-of-field organs (as dose–volume histograms) outside the 5% isodose for any isocentric treatment using coplanar beams [including intensity modulated radiotherapy and volumetric modulated arc therapy (VMAT)]. The model was configured with the corresponding Monte Carlo simulation of the peripheral absorbed dose for a 6 MV abdomen treatment on the International Comission on Radiological Protection (ICRP) 110 computational phantom. It was then validated with experimental measurements using thermoluminescent dosimeters in the male ATOM anthropomorphic phantom irradiated with a VMAT treatment for prostate cancer. Additionally, its performance was challenged by applying it to a lung radiotherapy treatment very different from the one used for training. The model agreed well with measurements and simulated dose values. A graphical user interface was developed as a first step to making this work more approachable to a daily clinical application.
CHAIRS: A choice-based air transport simulator applied to airline competition and revenue management
(2022) Fukushi Estay, Mitsuyoshi Andres; Delgado Breinbauer, Felipe Alberto; Raveau Feliú, Sebastián; Santos, Bruno F.
In Revenue Management (RM) systems, information censoring and the interaction between the forecasting and optimization stages, increases the costs and complexity of performance analysis using historical data. An affordable and suitable alternative is using simulations, but appropriate behavioral models must be considered. In the following document, we discuss and test the implementation of a dynamic air transport market simulator, designed to analyze RM systems. The simulator replicates the behavior of passengers that book seats offered in multiple flights by different airlines. We use discrete choice models to replicate the demand behavior, accounting for preferences and decision rule heterogeneity, and including a temporal evolution of the preference throughout the selling horizon. To replicate the supply behavior, a number of airlines modify the price and quantity of different fare classes offered in each flight, using a variety of RM forecasting, un-constraining, and optimization techniques. The simulator allows analysts to study the economic benefit of RM systems under predefined assumptions in an artificial and controlled environment. This increases the benefits obtained by the correct selection of context-appropriate RM systems and the likelihood of successfully implementing new and complex systems. We test and showcase the simulator performance, studying the entrance of a new airline in a competitive context. We generate, implement and evaluate different RM strategies in response to the introduction of new competition, and discuss the results, highlighting the interpretability and accuracy of the proposed framework.
Chilean University Students’ Digital Learning Technology Usage Patterns and Approaches to Learning
(2022) González Ugalde, Carlos Hugo; López, Dany; Calle Arango, Lina; Montenegro, Helena; Clasing, Paula
Purpose: This study aims to explore Chilean students’ digital technology usage patterns and approaches to learning. Design/Approach/Methods: We conducted this study in two stages. We worked with one semester learning management systems (LMS), library, and students’ records data in the first one. We performed a k-means cluster analysis to identify groups with similar usage patterns. In the second stage, we invited students from emerging clusters to participate in group interviews. Thematic analysis was employed to analyze them. Findings: Three groups were identified: 1) Digital library users/high performers, who adopted deeper approaches to learning, obtained higher marks, and used learning resources to integrate materials and expand understanding; 2) LMS and physical library users/mid-performers, who adopted mainly strategic approaches, obtained marks close to average, and used learning resources for studying in an organized manner to get good marks; and 3) Lower users of LMS and library/mid-low performers, who adopted mainly a surface approach, obtained mid-to-lower-than-average marks, and used learning resources for minimum content understanding. Originality/Value: We demonstrated the importance of combining learning analytics data with qualitative methods to make sense of digital technology usage patterns: approaches to learning are associated with learning resources use. Practical recommendations are presented.
Cross-Cultural Comparisons of Home Numeracy and Literacy Environments: Canada, Mexico, and Chile
(MDPI, 2022) Susperreguy Jorquera, María Inés; Jiménez Lira, Carolina; LeFevre, Jo-Anne
Home numeracy and literacy environments are related to the development of children’s early academic skills. However, the home learning environments of preschool children have been mainly explored with children from North America, Europe, and Asia. In this study we assessed the home numeracy and literacy environments of three-to-five-year-old children from Mexico (n = 54) and Chile (n = 41) and compared the patterns of results to those of children from Canada (n = 42). Parents completed a questionnaire about their expectations for children’s academic performance prior to Grade 1 and the home numeracy and literacy activities they provide for their children. To analyze differences among countries in the home learning environments, we performed mixed and one-way ANOVAs (Analysis of Variance), followed-up by post-hoc comparisons. Mexican parents had higher expectations for children’s early skills than Chileans or Canadians. The frequency with which Mexican, Canadian, and Chilean parents reported home numeracy and literacy activities showed both similarities and differences. Our findings speak to the importance of developing culturally sensitive models of early home learning environments and illustrate the complexities of comparing home learning environments across countries.
Eating contexts determine the efficacy of nutrient warning labels to promote healthy food choices
(Frontiers Media S.A., 2023) Caballero Vivanco, Sara; Moenne Vargas, Cristóbal Matías; Delgado Bravo, Mauricio Antonio; Luarte Rodríguez, Luis Nicolás; Jiménez, Yanireth; Galgani Fuentes, José Eduardo; Perez Leighton, Claudio
Introduction: Unhealthy food choices increase the risk of obesity and its co-morbidities. Nutrition labels are a public health policy that aims to drive individuals toward healthier food choices. Chile has been an example of this policy, where mandatory nutrient warning labels (NWL) identify processed foods high in calories and critical nutrients. Eating contexts influence individual food choices, but whether eating contexts also influence how NWL alter the decision process and selection during food choice is unknown. Methods: In an online mouse-tracking study, participants prompted to health, typical, or unrestricted eating contexts were instructed to choose between pairs of foods in the presence or absence of NWL. Conflict during choices was analyzed using mouse paths and reaction times. Results: NWL increased conflict during unhealthy food choices and reduced conflict during healthy choices in all contexts. However, the probability that NWL reversed an unhealthy choice was 80% in a healthy, 37% in a typical, and 19% in an unrestricted context. A drift-diffusion model analysis showed the effects of NWL on choice were associated with an increased bias toward healthier foods in the healthy and typical but not in the unrestricted context. Discussion: These data suggest that the efficacy of NWL to drive healthy food choices increases in a healthy eating context, whereas NWL are less effective in typical or unrestricted eating contexts.
Fare evasion on public transport: Who, when, where and how?
(2022) Cantillo Torregrosa, Luis Ángel; Raveau Feliú, Sebastián; Muñoz Abogabir, Juan Carlos
Transantiago, the public transport system of Santiago, Chile, has one of the highest fare evasion rates registered worldwide. The official statistics for late 2019 indicated that the evasion rate in bus legs was 26.6% while in metro it was almost 0%. This is a relevant issue due to the impacts of fare evasion on finances and quality of service, as budget constraints put pressure on the transit system. Analysing and understanding fare evasion should be the starting point for proposing solutions that could reduce it. Therefore, in this research we seek to answer the question of who are the evaders, when and where evasion happens and how is the fare evaded on public transport. To answer these questions, extensive data was gathered onboard buses of Transantiago for five full days (19 h a day) of operation, including weekdays and weekend. A total of 10,559 individual records were collected. The information considers age and gender of travellers, and fare evasion was measured in zones of Santiago that are characterised by very different economic conditions. Records also differ in terms of bus occupancy, presence of turnstiles in the buses, and types of stops (with and without off-board payment). Based on the collected information, a Binomial Logit model was calibrated to understand and explain fare evasion, quantifying the effect of different types of explanatory variables. Results show that fare evasion is higher for young men, evening and night periods, low-income neighbourhoods, crowded buses without turnstiles, bus stops without off-board payment and weak accessibility to metro stations and fare vending machines. The model does not only allows the identification of these trends, but is also able to quantify them. Based on the results, potential proposed solutions to tackle evasion are discussed.
Flavonoids and triterpenes isolated from Eucryphia cordifolia (Cunoniaceae)
(2022) Viteri Espinoza, Rafael Antonio; Giordano Villatoro, Ady; Montenegro Rizzardini, Gloria; Zacconi, Flavia C. M.
The phytochemical study of the leaves of Eucryphia cordifolia (Cunoniaceae) allowed for the isolation of six compounds: the triterpenes betulin (1) and 28-acetoxy betulin (3), the steroid β-sitosterol (2), the flavonol quercetrin (4), the flavanonol astilbine (5) and the flavanol catechin (6). The structures of the isolated compounds were clearly assigned through 1D and 2D-NMR, MS studies, and compared to previously described data. This is the first report on the isolation of compounds 1–4 and 6 from the genus Eucryphia. The chemotaxonomic importance of the isolated compounds within the family of Cunoniaceae-related plants is discussed.
Home mathematics environment and math performance of Chilean students in kindergarten and Grades 1 to 3
(Elsevier Ltd, 2022) Susperreguy Jorquera, María Inés; Di Lonardo Burr, Sabrina; Douglas, Heather; Xu, Chang; LeFevre, Jo-Anne; Río, María Francisca del; Salinas Ulloa, Viviana Monzerrat
We investigated whether home math activities were related to children's math performance in kindergarten and the first three years of primary school. Participants were Chilean parents and their children in kindergarten, Grade 1, Grade 2, and Grade 3 (ns = 101, 95, 87, and 84, respectively). Mothers and fathers independently answered questions about their math activities at home, provided sociodemographic information, and completed an arithmetic fluency task. Children completed measures of applied problem solving, calculation, and arithmetic fluency. For kindergarten children, we found that mothers’ (but not fathers’) reports of the frequency of operational (e.g., mental arithmetic) activities were positively related to children's math performance, whereas mothers’ reports of the frequency of mapping (e.g., counting, number naming) math activities were negatively correlated with performance. For children in Grades 1–3, home math activities were not significant unique predictors of math outcomes. The socioeconomic status of children's schools and maternal math fluency predicted children's math performance in Grades 1–3. The implications of these findings are discussed for understanding how children's home environments are related to their mathematical development.
Narratives Around Civil–Military Cooperation: How Institutionalized Discourses Influence Learning in Peace Operations
(2022) Jenne, Nicole
This article is concerned with narratives about the relation between the military and civilians. Narratives, dominant institutionalized discourses, influence how individuals learn by providing frames of reference which moderate the acquisition of new knowledge. Although the importance of narratives for institutional behavior has been recognized in the field of security studies, little attention has been paid to how they influence learning. This article presents a framework to analyze narratives in the context of learning based on the case of peace operations. Using qualitative case studies for theory-building, I argue that narratives on the closeness between the military and “the people” ease pressures to improve the military’s engagement with civilians and render peacekeepers less inclined to learn. All else equal, the absence of entrenched ideas about military–society relations facilitates the acquisition of new knowledge and skills in civil–military cooperation.
School environments and obesity: a systematic review of interventions and policies among school-age students in Latin America and the Caribbean
(Springer Nature, 2022) Vega Salas, María Jesús; Murray, Claudia; Nunes, Richard; Hidalgo-Arestegui, Alessandra; Curi-Quinto, Katherine; Penny, Mary E.; Cueto, Santiago; Lovegrove, Julie Anne; Sánchez, Alan; Vimaleswaran, Karani Santhanakrishnan
Background: The rapid rise in obesity rates among school children in Latin America and the Caribbean (LAC) could have a direct impact on the region’s physical and mental health, disability, and mortality. This review presents the available interventions likely to reduce, mitigate and/or prevent obesity among school children in LAC by modifying the food and built environments within and around schools. Methods: Two independent reviewers searched five databases: MEDLINE, Web of Science, Cochrane Library, Scopus and Latin American and Caribbean Health Sciences Literature for peer-reviewed literature published from 1 January 2000 to September 2021; searching and screening prospective studies published in English, Spanish and Portuguese. This was followed by data extraction and quality assessment using the Cochrane risk-of-bias tool (RoB 2) and the Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I), adopting also the PRISMA 2020 guidelines. Due to the heterogeneity of the intervention’s characteristics and obesity-related measurements across studies, a narrative synthesis was conducted. Results: A total of 1342 research papers were screened, and 9 studies were included; 4 in Mexico, and 1 each in Argentina, Brazil, Chile, Colombia, and Ecuador. Four studies reported strategies for modifying food provision; four other targeted the built environment, (modifying school premises and providing materials for physical activity); a final study included both food and built environment intervention components. Overall, two studies reported that the intervention was significantly associated with a lower increase over time in BMI/obesity in the intervention against the control group. The remaining studies were non-significant. Conclusions: Data suggest that school environmental interventions, complementing nutritional and physical education can contribute to reduce incremental childhood obesity trends. However, evidence of the extent to which food and built environment components factor into obesogenic environments, within and around school grounds is inconclusive. Insufficient data hindered any urban/rural comparisons. Further school environmental intervention studies to inform policies for preventing/reducing childhood obesity in LAC are needed.
Shared Components of Worldwide Successful Sexuality Education Interventions for Adolescents: A Systematic Review of Randomized Trials
(2023) Torres Cortés, Betzabé Carolina; Leiva, Loreto; Canenguez, Katia; Olhaberry Huber, Marcia; Méndez Hernández, Emmanuel Joshua
A crucial aspect of human development is sexuality which has implications for health, particularly in adolescence, since unfavorable sexual experiences may result in physical and mental problems. Sexuality education interventions (SEI) are one of the most used actions to promote sexual health in adolescents. Nevertheless, there is variability across their components; therefore, key elements for an effective SEI targeted at adolescents (A-SEI) are not well known. Based on this background, this study aims to identify the shared components of successful A-SEI through a systematic review of randomized controlled trials (RCT). This study followed the preferred reporting items for systematic reviews and meta-analyses statement. A search was conducted in CINAHL, PsycInfo, PubMed, and Web of Science between November and December 2021. A total of 21 studies passed the inclusion test after the review of 8318 reports. A total of 18 A-SEIs were identified in these studies. The components analyzed were the intervention’s approach, dose, type of intervention, theoretical framework, facilitators’ training, and intervention methodology. The results established that components that should be present in the design of an effective A-SEI are behavior change theoretical models, the use of participatory methodology, be targeted at mixed-sex groups, facilitators’ training, and at least ten hours of weekly intervention.
Who leads peace operations? A new dataset on leadership positions in UN peace operations, 1948–2019
(2022) Jenne, Nicole
It is widely recognized that UN peace operations have been critically influenced by their leadership personnel in the field since the first UN peacekeepers were deployed in 1948. But who exactly are the people that lead peace operations and decide how these are implemented on the ground? This special data feature introduces a new dataset on leadership positions in UN peace operations from its interception in 1948 up to 2019. The relevance of different authorities in peace operations is discussed, followed by an examination of general trends in the data with regards to the duration of term in different leadership positions, the national and regional origin of peace operations authorities, and the distribution of gender. It is shown that scholars studying a variety of topics, including policymaking at the UN, the use of force in peace operations, international responsibilities, and the role of the global south in international politics, can benefit from paying closer attention to the question of who occupies leadership positions in UN peace operations.

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