Manuel A. Bolívar

Bio: Manuel A. Bolívar is an academic researcher from University of Los Andes. The author has contributed to research in topics: Yen's algorithm & Support vector machine. The author has an hindex of 6, co-authored 6 publications receiving 116 citations.

Active streets for children: The case of the Bogotá Ciclovía.

Abstract: Introduction The Ciclovia is a worldwide program in which streets are temporarily closed to motorized transport to create a space for recreation and outdoor play among children and adults. The aim of this study was to assess the associations between physical activity (PA), sedentary time (SED), body mass index and Ciclovia participation among children aged 9 to 13 years. Methods All students in the 4th and 5th grades from the selected schools were invited to participate in the study. The study included 923 children. PA and SED were measured using waist-worn accelerometers, and height and weight were measured using standardized procedures. Ciclovia participation was self-reported. The analyses included multilevel linear, generalized mixed and generalized additive models. Results The mean age of the sample was 10.1±0.7 years, and 49.5% were boys. In the last year, 46% of the children participated in the Ciclovia, and 34% reported participating frequently (at least once per month). No differences were found in the mean minutes of moderate-to-vigorous PA on weekdays between frequent Ciclovia users and sporadic and non-Ciclovia users (72 vs 69; p = 0.09). In contrast, frequent Ciclovia users had higher moderate-to-vigorous PA on Sundays than sporadic and non-Ciclovia users (65.6 vs 59.2; p = 0.01), specifically between the hours of 12:00 and 16:00. In addition, frequent Ciclovia users did not differ from the sporadic and non-Ciclovia users in SED (515.3 vs 521.3; p = 0.19). Frequent Ciclovia users had lower SED on Sundays than the sporadic and non-Ciclovia users (437.7 vs 456.5; p = 0.005). Additionally, frequent Ciclovia users were more likely to be overweight (28.3% vs 20.4% p = 0.01). We did not find differences in participation by sex, and low-to-middle income children were more likely to participate. Conclusions The Ciclovias offer an innovative, inclusive recreational space and consequently provide opportunities to increase moderate-to-vigorous PA and reduce SED among children.

Acceleration strategies for the weight constrained shortest path problem with replenishment

Abstract: The weight constrained shortest path problem with replenishment (WCSPP-R) generalizes the constrained shortest path problem (CSP) and has multiple applications in transportation, scheduling, and telecommunications. We present an exact algorithm based on a recursive depth-first search that combines and extends ideas proposed in state-of-the-art algorithms for the CSP and the WCSPP-R. The novelty lies in a set of acceleration strategies that significantly improves the algorithm’s performance. We conducted experiments over large real-road networks with up to 6 million nodes and 15 million arcs, achieving speedups of up to 219 times against the state-of-the-art algorithm.

Effects of a strategy for the promotion of physical activity in students from Bogotá.

Abstract: OBJECTIVE To examine the effect of the promotion of physical activity during recess on the levels of physical activity, sedentary behaviors, and adiposity of Colombian students. METHODS Three schools were randomly selected by an intervention group in Bogota, Colombia, in 2013: Intervention (Active Module of Active Recess – MARA) + Text Messages (SMS) (MARA+SMS group), intervention (MARA group), control (control group). Intervention was implemented for ten weeks. The duration and intensity of physical activity and sedentary behaviors were measured objectively using accelerometers Actigraph-GT3X+. Adiposity was measured by body mass index and fat percentage. We measured at baseline (T0) and during the tenth week of intervention (T1). We evaluated the effect of the intervention using a difference-in-difference analysis (DID). RESULTS We included 120 students (57.5% girls; mean age = 10.5 years; standard deviation [SD] = 0.64). There was a significant increase in the mean daily minutes of moderate to vigorous physical activity in the MARA group (Difference T1-T0 = 6.1 minutes, standard error [SE] = 3.49, p = 0.005) in relation to the control group. There were no significant changes in the minutes of moderate to vigorous physical activity in the MARA+SMS group (Difference T1-T0 = -1.0 minute; SE = 3.06; p = 0.363). The minutes decreased in the control group (Difference T1-T0 = -7.7 minutes; SE = 3.15; p = 0.011). The minutes of sedentary behaviors decreased in the MARA and MARA+SMS groups and increased in the control group (MARA Difference T1-T0 = -15.8 minutes; SE = 10.05; p= 0.279; MARA+SMS Difference T1-T0 = -11.5 minutes; SE = 8.80; p= 0.869; Control Difference T1-T0 = 10.9 minutes; SE = 9.07; p = 0.407). There was a higher participation in the MARA group in relation to the MARA+SMS group (MARA group = 34.4%; MARA+SMS group = 12.1%). There were no significant changes in adiposity at 10 weeks according to difference-in-differences analysis (body mass index p: ΔMARA+SMS group versus Δcontrol group = 0.945, ΔMARA group versus Δcontrol group = 0.847, ΔMARA+SMS group versus ΔMARA group = 0.990; FP p ΔMARA+SMS group versus Δcontrol group = 0.788, ΔMARA group versus Δcontrol group = 0.915, ΔMARA+SMS group versus ΔMARA group = 0.975). CONCLUSIONS The Active Module of Active Recess is a promising strategy to increase physical activity levels and decrease sedentary behavior in students. The addition of Text Messages was not associated with increased moderate to vigorous physical activity or changes in adiposity.

Socioeconomic differences in lack of recreational walking among older adults : the role of neighbourhood and individual factors

Abstract: Background: People with a low socioeconomic status (SES) are more likely to be physically inactive than their higher status counterparts, however, the mechanisms underlying this socioeconomic gradient in physical inactivity remain largely unknown. Our aims were (1) to investigate socioeconomic differences in recreational walking among older adults and (2) to examine to what extent neighbourhood perceptions and individual cognitions regarding regular physical activity can explain these differences.----- Methods: Data were obtained by a large-scale postal survey among a stratified sample of older adults (age 55–75 years) (N = 1994), residing in 147 neighbourhoods of Eindhoven and surrounding areas, in the Netherlands. Multilevel logistic regression analyses assessed associations between SES (i.e. education and income), perceptions of the social and physical neighbourhood environment, measures of individual cognitions derived from the Theory of Planned Behaviour (e.g. attitude, perceived behaviour control), and recreational walking for ≥10 minutes/week (no vs. yes).----- Results: Participants in the lowest educational group (OR 1.67 (95% CI, 1.18–2.35)) and lowest income group (OR 1.40 (95% CI, 0.98–2.01)) were more likely to report no recreational walking than their higher status counterparts. The association between SES and recreational walking attenuated when neighbourhood aesthetics was included in the model, and largely reduced when individual cognitions were added to the model (with largest effects of attitude, and intention regarding regular physical activity). The assiation between poor neighbourhood aesthetics and no recreational walking attenuated to (borderline) insignificance when individual cognitions were taken into account.----- Conclusion: Both neighbourhood aesthetics and individual cognitions regarding physical activity contributed to the explanation of socioeconomic differences in no recreational walking. Neighbourhood aesthetics may explain the association between SES and recreational walking largely via individual cognitions towards physical activity. Intervention and policy strategies to reduce socioeconomic differences in lack of recreational walking among older adults would be most effective if they intervene on both neighbourhood perceptions as well as individual cognitions.

Machine Learning in Predictive Maintenance towards Sustainable Smart Manufacturing in Industry 4.0

Abstract: Recently, with the emergence of Industry 4.0 (I4.0), smart systems, machine learning (ML) within artificial intelligence (AI), predictive maintenance (PdM) approaches have been extensively applied in industries for handling the health status of industrial equipment. Due to digital transformation towards I4.0, information techniques, computerized control, and communication networks, it is possible to collect massive amounts of operational and processes conditions data generated form several pieces of equipment and harvest data for making an automated fault detection and diagnosis with the aim to minimize downtime and increase utilization rate of the components and increase their remaining useful lives. PdM is inevitable for sustainable smart manufacturing in I4.0. Machine learning (ML) techniques have emerged as a promising tool in PdM applications for smart manufacturing in I4.0, thus it has increased attraction of authors during recent years. This paper aims to provide a comprehensive review of the recent advancements of ML techniques widely applied to PdM for smart manufacturing in I4.0 by classifying the research according to the ML algorithms, ML category, machinery, and equipment used, device used in data acquisition, classification of data, size and type, and highlight the key contributions of the researchers, and thus offers guidelines and foundation for further research.

Understanding the rise of cardiometabolic diseases in low- and middle-income countries

Abstract: Increases in the prevalence of noncommunicable diseases (NCDs), particularly cardiometabolic diseases such as cardiovascular disease, stroke and diabetes, and their major risk factors have not been uniform across settings: for example, cardiovascular disease mortality has declined over recent decades in high-income countries but increased in low- and middle-income countries (LMICs). The factors contributing to this rise are varied and are influenced by environmental, social, political and commercial determinants of health, among other factors. This Review focuses on understanding the rise of cardiometabolic diseases in LMICs, with particular emphasis on obesity and its drivers, together with broader environmental and macro determinants of health, as well as LMIC-based responses to counteract cardiometabolic diseases. The rise of cardiometabolic diseases in low- and middle-income countries is tied to a multitude of environmental, social and commercial determinants, which are discussed in this Review along with a strategy to counteract those factors.