Trisections of 4-manifolds with Boundary

Given a handle decomposition of a 4-manifold with boundary, and an open book decomposition of the boundary, we show how to produce a trisection diagram of a trisection of the 4-manifold inducing the given open book. We do this by making the original proof of the existence of relative trisections more explicit, in terms of handles. Furthermore, we extend this existence result to the case of 4-manifolds with multiple boundary components, and show how trisected 4-manifolds with multiple boundary components glue together.Comment: 17 pages, 12 figure

Systemic intervention for computer-supported collaborative learning

This paper presents a systemic intervention approach as a means to overcome the methodological challenges involved in research into computer-supported collaborative learning applied to the promotion of mathematical problem-solving (CSCL-MPS) skills in schools. These challenges include how to develop an integrated analysis of several aspects of the learning process; and how to reflect on learning purposes, the context of application and participants' identities. The focus of systemic intervention is on processes for thinking through whose views and what issues and values should be considered pertinent in an analysis. Systemic intervention also advocates mixing methods from different traditions to address the purposes of multiple stakeholders. Consequently, a design for CSCL-MPS research is presented that includes several methods. This methodological design is used to analyse and reflect upon both a CSCL-MPS project with Colombian schools, and the identities of the participants in that project

Uso del tabaco entre los jóvenes colombianos Retos para los profesionales en salud pública

Resumen El incremento en el índice del uso del tabaco y sus derivados entre los jóvenes colombianos representa un llamado para los especialistas en salud pública para que consideren el control del tabaco una prioridad en el área de prevención. El objetivo de este artículo es documentar los daños del tabaco en el cuerpo humano, el incremento del tabaquismo entre los jóvenes colombianos, y explorar el papel de los programas de prevención en la reducción de este problema. Palabra claves: Salud, juventud, tabaco, prevención. Abstract Increasing tobacco use rates among Colombian youth exemplify the need to make prevention top public health priority. The purpose of this article is to document the adverse effects of tobacco in the human body, the increases in tobacco use among Colombian youth, and to explore the role of prevention in decreasing this public health problem. Key words: Healt, young, tabacco, prevention

Seismic site classification from the horizontal-to-vertical response spectral ratios: use of the Spanish strong-motion database

Normally, the average of the horizontal-to-vertical (H/V) ratios of the 5% damped response spectra of ground motions is used to classify the site of strong-motion stations. In these cases, only the three-orthogonal as-recorded acceleration components are used in the analysis, and all the vector compositions that can generate a different response for each period oscillator are excluded. In this study, the Spanish strong-motion database was used to classify the sites of accelerometric stations based on the predominant periods through the average horizontal-to-vertical spectral ratios (HVSR) of recorded ground motions. Moreover, the directionality effects using the vector composition of the horizontal components of ground motions were also considered in the estimations of H/V ratios. This consideration is a relevant novelty compared to the traditional H/V ratios methods. Only earthquakes with magnitudes above 3.5 and hypocentral distances below 200 km were selected, which resulted in 692 ground-motion records, corresponding to 86 stations, from events in the period between 1993 and 2017. After the analysis, a predominant-period site classification was assigned to each station. On the whole, the obtained mean and standard deviation values of the spectral ratios are comparable to those shown by other researchers. Therefore, the advantages of the proposed procedure, which takes the directionality effects into account, can be summarized as follows: (a) The obtained information is richer and gives enables more sophisticated and realistic analyses on the basis of percentiles and (b) it is easier to detect anomalous stations, sites, and/or accelerograms. Moreover, the method eliminates the effect of directionality as a contributor to epistemic uncertainty.Peer ReviewedPostprint (published version

I bet you don’t look good on the dance floor: Re-examining the innovation policy dance metaphor in the case of Colombia

Innovation heuristics offer guidance on how to navigate through the complex dynamics of innovation governance. However, further discussion is needed on the premises of such analytical tools to inquire on their implications on innovation policy and practice. This paper builds on the innovation policy dance metaphor to better grasp the ever-changing interplays (or dance) between innovation practice (I), policy (P) and theory (T). We critically assess the basic underlying assumptions of this metaphor, by examining the extent to which its heuristic pretensions are relevant in the Latin American context. To do so, we explore three illustrative cases in Colombia, shedding light on some crosscutting opportunities and gaps for the dancing metaphor across different innovation I-P-T situations. Some derived lessons suggest that dancing occurs within and/or between different governance levels, where variables such as politics shape the innovation I-P-T interplay and time defines first and second order learning pathways

Work-related injuries among child street-laborers in Latin America: Prevalence and predictors

Objectives. To determine the prevalence and nature of occupational injuries among children working in the streets of four major cities in Latin America, as well as to identify factors that predict these work-related injuries. Methods. This cross-sectional study interviewed 584 children from 5-17 years of age working on the streets of Bogota, Colombia; Lima, Peru; Quito, Ecuador; and São Paulo, Brazil. Descriptive analyses and multivariate logistic regressions were conducted, with incidence and serious injuries regressed on occupational and sociodemographic variables. Results. Approximately 39.6% of the child street-laborers surveyed reported an injury sustained while working in the streets: scratches (19.5%), cuts/lacerations (16.4%), bums (8.6%), car accidents (8.9%), sprains (4.6%), and amputations (0.3%). Working a high number of daytime hours and performing on the street predicted the greatest risk of injury, even after controlling for sociodemographic factors; specifically, each additional hour of daytime work increased the risk of injury by 1.4%. Child performers had three times the injury rate of children primarily selling products. Boys, older children, and children in Quito were more likely to experience moderate-to-severe injuries, than girls, younger children, and street children in the other study cities. Conclusions. Interventions are needed to address the substantial risk of injury experienced by children working on the city streets of Latin America

Termodinamičko ispitivanje prijelaza acetanilida i fenacetina iz vode u organska otapala

The molar (KCo/w) and rational (KXo/w) partition coefficients in the octanol/buffer, i-propyl myristate/buffer, chloroform/buffer, and cyclohexane/buffer systems were determined for acetanilide and phenacetin at 25.0, 30.0, 35.0, and 40.0 °C. In all cases except for cyclohexane, the KCo/w and KXo/w values were greater than unity. This demonstrates that these two drugs have predominantly lipophilic behavior. Gibbs and van\u27t Hoff thermodynamic analyses have revealed that the transfer of these drugs from water to organic solvents is spontaneous and that it is mainly driven enthalpically for i-propyl myristate and chloroform, and entropy-driven for octanol and cyclohexane.U radu su određeni molarni (KCo/w) i razdjelni (Kxo/w) particijski koeficijenti acetanilida i fenacetina u sustavima oktanol/pufer, i-propil-miristat/pufer, kloroform/pufer i cikloheksan/pufer na 25,0, 30,0, 35,0 i 40 C. U svim slučajevima osim za cikloheksan, vrijednosti KCo/w i Kxo/w bile su veće od jedan. To ukazuje da su ova dva lijeka pretežno lipofilna. Gibbsova i van’t Hoffova termodinamička analiza su otkrile da je prijelaz tih lijekova iz vode u organska otapala spontan i da su uglavnom pokrenuti entalpijski za i-propil-miristat i kloroform te entropijski za oktanol i cikloheksan

Termodinamičko ispitivanje prijelaza acetanilida i fenacetina iz vode u organska otapala

The molar (KCo/w) and rational (KXo/w) partition coefficients in the octanol/buffer, i-propyl myristate/buffer, chloroform/buffer, and cyclohexane/buffer systems were determined for acetanilide and phenacetin at 25.0, 30.0, 35.0, and 40.0 °C. In all cases except for cyclohexane, the KCo/w and KXo/w values were greater than unity. This demonstrates that these two drugs have predominantly lipophilic behavior. Gibbs and van\u27t Hoff thermodynamic analyses have revealed that the transfer of these drugs from water to organic solvents is spontaneous and that it is mainly driven enthalpically for i-propyl myristate and chloroform, and entropy-driven for octanol and cyclohexane.U radu su određeni molarni (KCo/w) i razdjelni (Kxo/w) particijski koeficijenti acetanilida i fenacetina u sustavima oktanol/pufer, i-propil-miristat/pufer, kloroform/pufer i cikloheksan/pufer na 25,0, 30,0, 35,0 i 40 C. U svim slučajevima osim za cikloheksan, vrijednosti KCo/w i Kxo/w bile su veće od jedan. To ukazuje da su ova dva lijeka pretežno lipofilna. Gibbsova i van’t Hoffova termodinamička analiza su otkrile da je prijelaz tih lijekova iz vode u organska otapala spontan i da su uglavnom pokrenuti entalpijski za i-propil-miristat i kloroform te entropijski za oktanol i cikloheksan