Universidad de La Salle
  • Bogotá, Colombia
Recent publications
Haiti has become a scenario of convergence between the political and the criminal as a combination for territorial control and security configuration. Using process tracing, we wanted to find what were the motivations for hiring a group of mercenaries with the aim of getting rid of an increasingly authoritarian president. Thus we identify critical points in Haitian history regarding the symbiosis between crime and political institutions, which permit us to construct causal mechanisms to identify that, among other things, Haiti is a phantom state, as we call it in our research, because it has a nominal and supplanted political structure in which competition between different groups who seek to assume political authority has led to a limited, fragmented, delegated and authoritarian presence of the state among the population and the territory. Consequently, we find that the use of force has not belonged exclusively to the state, it has been divided into different oligopolies of violence and the Haitian state is only one more actor in the criminal complex of the country, where state institutions are the mechanisms with criminal organizations to generate criminal dynamics of territorial control and profit. Based on the above, we consider that, as the government of Jovenel Moïse had allied with the strongest gangs and weakened political groups and criminal rivals, the mercenaries were the instrument to break the authoritarian government of Moïse. In effect, the magnicide was the product of a plan to depose the president, undertaken by political leaders in complicity with the country’s judiciary to curb the concentration of executive power.
The effect of nanosilica under the influence of dispersing agents on the fresh empirical and fundamental rheological properties of self-compacting concrete (SCC) is a complex phenomenon which has been investigated in this paper. Models to predict the rheological properties of nanosilica blended SCC are also lacking to avoiding/saving comprehensive and costly rheology laboratory trials mainly when these tests are unavailable or limited. To these ends, 315 laboratory tests were performed on 15 blended SCC mixtures, manufactured using five nanosilica dosages, 0%, 0.5%, 1%, 1.5% 2%, and three dispersing superplasticizer dosages, 0.62%, 0.66% 0.70%, by weight of cement. Fundamental rheological properties of the SCC mixes were assessed by using a rotational concrete rheometer based on the nonlinear modified Binghamian model. Results showed that SCC mixes are sensitive to nanosilica and superplasticizer admixtures producing a complex non-linear effect on their empirical and rheological properties. Based on these trends, eleven empirical models were proposed to predict the fresh empirical and rheological properties of the SCC mixes. A statistical analysis demonstrated the good fitting of the proposed models with the measured properties of SCC mixes during the laboratory trials. These models could serve for design and production of nanosilica blended SCC as alternative approach.
Los bosques secos tropicales (BST) son uno de los ecosistemas más amenazados de Colombia, con remanentes de estos concentrados en bosques riparios. Este trabajo estudió la vegetación de un bosque ripario ubicado dentro de un remanente de BST en la cuenca alta del río Magdalena mediante el uso de transectos en tres estaciones a lo largo del arroyo La Avería (Paicol, Huila, Colombia). Se encontraron 199 individuos distribuidos en 47 especies. La composición florística fue semejante a la de otros BST, mientras que el número de individuos fue menor. Fabaceae fue la familia más representada y Zygia longifolia y Guadua angustifolia las especies con mayor Índice de Valor de Importancia (IVI). Se concluyó que el bosque ha sido sometido a perturbaciones antrópicas y se encuentra en una etapa sucesional temprana. Además, se encontraron diferencias en el grado de conservación del bosque entre las tres estaciones muestreadas.
Base isolation solutions are efficient alternatives for seismic protection of buildings and for enhancing resilient capacity. Currently, seismic isolation is focused principally on the critical infrastructure of public health, transportation, education, etc. Despite these considerations, the current worldwide implementation of this technology is still insufficient. A crucial step to be taken into the promotion of any earthquake-resistant construction technique is the development of design codes that, although being inspired in the major international regulations, account for the local seismic effects, among other factors. With the aim of assisting code developers, this work analyzes and compares the code requirements for seismic base isolation in Japan, China, Russia, Italy, USA, and Chile. Two prototype seismically isolated hospital buildings located in high and medium seismicity zones (Los Angeles and New Mexico, respectively) were analyzed and designed with the examined codes. It is concluded that there are high differences among some of their requirements even though the technology used is the same.
Residual biomass gasification is a promising route for the production of H2-rich syngas. However, the simultaneous formation of pollutants such as light hydrocarbons (HCs), benzene, toluene and xylenes (BTEX), polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during gasification must be controlled. As a result, this study evaluated the effect of temperature and catalytic reforming over a Rh-Pt/CeO2-SiO2 catalyst during steam gasification of sugarcane residual biomass on syngas composition and pollutant removal. The above was carried out in a horizontal moving reactor, an Amberlite XAD-2 polyaromatic resin was used to collect the contaminants and characterization of the catalyst was performed. In this study, a concentration of up to 37 mol% of H2, a yield of 23.1 g H2 kg⁻¹biomass, and a H2/CO ratio ≥2 were achieved when gasification and reforming were integrated. In addition, the catalyst characterization showed that Rh-Pt/CeO2-SiO2 was not susceptible to sintering and favored the formation of hydroxyl groups that promoted CO oxidation, thereby increasing the H2/CO ratio, as confirmed by in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). At 800 °C, where a high H2 yield was obtained, 209 g Nm⁻³ of light HCs and BTEX, 10.9 g Nm⁻³ of PAHs, and 32.5 ng WHO-TEQ Nm⁻³ of PCDD/Fs were formed after gasification. Interestingly, after catalytic reforming, 62% of light HCs and BTEX, 60% of PAHs, and 94% of PCDD/Fs were removed, leading to cleaner syngas with properties that allow it to be used in a wide range of energy applications.
“APIR: methodology for risk assessment and prioritization in HACCP plans”. Introduction: A prioritization methodology based on bottom-up risks is proposed for different hazards and food matrices. The variables of the model are subdivided into two categories: a) the characteristics of the hazard, where the probability of occurrence and severity are quantified. (b) the properties of the food matrix which estimate its epidemiological risk, presence in the food and vulnerability of its manufacture. A Risk Index (IR) is established as a parameter to facilitate food safety managers to discriminate and prioritize Significant Hazards during the hazard identification of HACCP plans. Objective: The aim of this work was to establish a flexible and dynamic methodology of prioritization based on risk for processing and processing companies of animal products intended for human consumption and integrate it with HACCP plans, allowing specific controls to be established in the production process. Results: The significance values between the clusters Nrp and Nrm were p<0,05. The Spearman Correlation Coefficient (rho) was estimated to determine the proportion of variation between the same predictors. The results obtained were Or-Nrp (rho= 0,719, p= <0,001), Se-Nrp (rho= 0,888, pvalor= <0,001), Re-Nrm (rho= 0,560, p-valor= <0,001), Pm- Nrm (rho= 0,696, p-valor= <0,001) y Vd (rho= 0,687, pvalor= <0,001), respectively. A case study is included to simulate the model and demonstrate its operability. Discussion: The results obtained demonstrate the replicability and validity of this model. The name APIR (Prioritization analysis based on Risk Index) is proposed for this methodology.
17α-estradiol (17α-E2) is referred to as a nonfeminizing estrogen that was recently found to extend healthspan and lifespan in male, but not female, mice. Despite an abundance of data indicating that 17α-E2 attenuates several hallmarks of aging in male rodents, very little is known with regard to its effects on feminization and fertility. In these studies, we evaluated the effects of 17α-E2 on several markers of male reproductive health in two independent cohorts of mice. In alignment with our previous reports, chronic 17α-E2 treatment prevented gains in body mass, but did not adversely affect testes mass or seminiferous tubule morphology. We subsequently determined that chronic 17α-E2 treatment also did not alter plasma 17β-estradiol or estrone concentrations, while mildly increasing plasma testosterone levels. We also determined that chronic 17α-E2 treatment did not alter plasma follicle-stimulating hormone or luteinizing hormone concentrations, which suggests 17α-E2 treatment does not alter gonadotropin-releasing hormone neuronal function. Sperm quantity, morphology, membrane integrity, and various motility measures were also unaffected by chronic 17α-E2 treatment in our studies. Lastly, two different approaches were used to evaluate male fertility in these studies. We found that chronic 17α-E2 treatment did not diminish the ability of male mice to impregnate female mice, or to generate successfully implanted embryos in the uterus. We conclude that chronic treatment with 17α-E2 at the dose most commonly employed in aging research does not adversely affect reproductive fitness in male mice, which suggests 17α-E2 does not extend lifespan or curtail disease parameters through tradeoff effects with reproduction.
This article examines the centrality of the participation of society in the peace process between the Colombian government and the National Liberation Army (ELN) that initiated during the Santos administration, in the light of readiness theory. It does so on the basis of over 60 interviews with key respondents, documents from delegations to the negotiating table, as well as secondary sources. It analyses the importance of this point for the ELN on ideological and pragmatic grounds, and the government's perspective on it. It argues that such a participation was key to rebalance the perceived power asymmetry between the government and ELN, increasing this guerrilla group's optimism about a dignified exit and hence its readiness to engage in talks. In particular, the ELN considered that, by making social groups stakeholders in the peace process, these groups could put pressure on the government to agree on, and implement, provisions towards social transformation. In so doing, this article contributes to debates on how to enhance weaker parties' readiness to negotiate an end to internal armed conflict, as well as on how public participation in peace processes could be useful in this regard.
Glaucoma is a common cause of visual loss and irreversible blindness, affecting visual and life quality. There are various mechanisms involved in retinal ganglion cell (RGC) apoptosis and functional and structural loss in the visual system. The prevalence of glaucoma has been increased in several countries. However, its early diagnosis has contributed to prompt attention. Molecular and cellular biological mechanisms are important for understanding the pathological process of glaucoma and new therapies. Thus, this review discusses the factors involved in glaucoma; from basic science to cellular and molecular events (e.g., mitochondrial dysfunction, reticulum endoplasmic stress, glutamate excitotoxicity, the cholinergic system, and genetic and epigenetic factors). Which in recent years, have been included in the development of new therapies, management, and diagnosis of this disease.
Los trazadores como método de medición y caracterización de la evolución de los flujos naturales, además de ofrecer información de la dinámica (advección) y la dispersión como fenómenos “locales” propiamente dichos, pueden dar información adicional, densa, sobre las condiciones globales (lejanas del punto de medición), en virtud de la conexión termodinámica que se establece entre todos los puntos del sistema cuando existe un estado estable en el cauce. Como ha sido estudiado ampliamente desde la segunda mitad del siglo pasado, esta condición de equilibrio dinámico (estado estable) en los flujos naturales para los fenómenos que no presentan una irreversibilidad pronunciada (región lineal de la termodinámica irreversible) implica una serie de características notables que simplifican la interpretación de los complejos fenómenos de las corrientes turbulentas y, por ende, de los procesos dispersivos que se superponen. Dentro de este enfoque, se define una función de estado, Φ(U, E, t), dependiente de la velocidad media del flujo, el coeficiente longitudinal de dispersión y el tiempo, que describe la evolución de la nube de trazador, de tal forma que en su calidad aproximada de potencial termodinámico permite descubrir y precisar ciertas particularidades del fenómeno. En este artículo se exploran las características y aplicaciones prácticas de estos principios. Se incluye además un análisis heurístico de las llamadas funciones directas rq(F) e inversas rq(F)-1, auxiliares a la función de estado F(U, E, t), que se utilizan tanto para la interpretación del tiempo del centroide como de los coeficientes de difusión-dispersión longitudinal y transversal. Estas funciones fueron aplicadas experimentalmente en la quebrada “La Vieja” de la ciudad de Bogotá, presentando buena concordancia con los referentes teóricos. Con este tema se pretende ofrecer una herramienta teórico-practica para entender cabalmente estos procesos, que tienen tanto interés para la modelación y control de las contaminaciones hídricas.
Skilled labor, R&D, and knowledge-based inter-organizational networks are important resources for innovation. The relationship between information technology (IT) investments and innovation outcomes is less well understood. It is unclear whether IT investments act as substitutes for or complements of these other resources to create innovation capabilities, and how such relationships play out over time. Based on panel data from 393 Colombian manufacturing firms between 2009 and 2017, we found that while IT investments alone do not improve innovation performance over time, they do when they are combined with the presence of an R&D unit. Furthermore, we found that IT investments substitute for (rather than complement) skilled labor to improve innovation performance over time and that their interaction with networks does not significantly affect innovation performance. Our findings contribute to the innovation literature on dynamic capabilities in understanding the role of IT in the combination of resources from a longitudinal perspective.
The visual system is regulated by the nervous system through neurotransmitters, which play an important role in visual and ocular functions. One of those neurotransmitters is acetylcholine, a key molecule that plays a diversity of biological functions. On the other hand, acetylcholinesterase, the enzyme responsible for the hydrolysis of acetylcholine, is implicated in cholinergic function. However, several studies showed that in addition to their enzymatic functions, Acetylcholinesterase exerts non-catalytic functions. In recent years, the importance of evaluating all possible functions of acetylcholine-acetylcholinesterase has been evidenced. Nevertheless, there is evidence that suggests cholinesterase activity in the eye can regulate some biological events both in structures of the anterior and posterior segment of the eye and therefore in the visual information that is processed in the visual cortex. Hence, the evaluation of cholinesterase activity could be a possible marker of alterations in cholinergic activity not only in ocular disease but also in systemic diseases.
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4,409 members
Diego Soler-Tovar
  • Facultad de Ciencias Agropecuarias
Patricia Hernández-Rodríguez
  • Basic Science Department
Alejandro Ramírez Hernández
  • Facultad de Ciencias Agropecuarias
Efrain Benavides
  • Grupo de Investigación Epidemiología y Salud Pública
Carlos Peña
  • Facultad de Ingeniería
Bogotá, Colombia