Análisis de la competencia y congestión en el mercado colombiano de gas natural por medio de simulación

Esta investigación analiza los principales sucesos que generan congestión en el sistema de transporte del mercado de gas natural en Colombia y su efecto en la competitividad económica sobre éste importante subsector energético. Se estudian las principales interacciones que se presentan entre los diversos actores del mercado (productores, comercializadores, transportadores, consumidores y reguladores). La investigación apunta a obtener un mayor conocimiento de la complejidad que introduce la congestión para dar señales claras de los requerimientos de inversión en expansión del sistema de transporte o de la oferta de producción. Para lograr esto, se desarrolló un modelo de simulación que representa el comportamiento diario del mercado colombiano de acuerdo a las condiciones de infraestructura y esquemas de comercialización bajo diferentes escenarios de demanda térmica y condiciones de abastecimiento en el futuro. El modelo toma los requerimientos de capacidad de transporte realizados por los productores y comercializadores y balancea los flujos a través de la red. El modelo es usado para comparar la operatividad del mercado bajo la reglamentación vigente y bajo diferentes esquemas propuestos para administrar la congestión de la red. / Abstract. We study the problem of gas supply availability in Colombia by focusing on the short-run operation of the pipeline network. Natural gas demand increases sharply during dry periods, when water for power generation is scarce but if there are transportation constraints, rationing rules favor regulated markets. Thus, congestion is one of the causes of gas supply shortages in the short-run. We examine the feasibility of increasing supply security by managing congestion in the gas network and finding alternative supply sources, rather than by expanding pipeline capacity. To achieve this, we simulate the gas network operation under the current regulatory framework and considering the interaction between suppliers, traders, distributors, and transporters of natural gas. The analysis of the system’s behavior and the simulation results indicate that high market uncertainty delays investments on new transportation and supply capacity. This, eventually, leads to congestion in the pipelines. The model results also show that some alternatives involving considerable investments, like Peak-Shaving and excessive expansion of transport capacity are not cost-effective for solving the long-run problems of congestion and security of supply in the market. Such alternatives work better when combined with other policies like liquefied gas imports (LNG). Options like LNG are also capital intensive, but they are able to improve the market performance in the long-termMaestrí

Evidence for subaerial development of the Caribbean oceanic plateau in the Late Cretaceous and palaeo-environmental implications

The formation of oceanic plateaus in the Pacific in the Mesozoic has been proposed to create major environmental impacts, including global anoxic events OAE-1 in the Aptian (ca. 120 Ma) and OAE-2 in the Cenomanian–Turonian (ca. 90 Ma). However, our understanding of the formation of these large volcanic systems and their environmental effects are strongly limited by difficulties in accessing them and characterising their volcanic evolution. In particular, it remains significant to determine whether Pacific oceanic plateaus experience a phase of subaerial volcanic activity as this has critical implications in terms of their environmental impacts. Herein we provide the first unequivocal evidence for an emergent volcanic phase of the Caribbean oceanic plateau in the Late Cretaceous. This subaerial phase is evidenced by accreted oceanic sequences in Colombia that include fallout tuffs with accretionary lapilli and lahar deposits. This facies assemblage, recognised for the first time in an oceanic plateau, reflects phreatomagmatic eruptions coeval with subaerial erosion on an oceanic island. This result, combined with previous evidence of subaerial development of the Ontong Java Plateau and Shatsky Rise, suggests that syn-volcanic emergence of oceanic plateaus was common in the Pacific during the Mesozoic. Although temporal and spatial scales of these emergences remain poorly constrained it confirms that emergence of the Caribbean plateau in the Late Cretaceous (ca. 90 Ma) could have actively contributed to atmospheric changes and the establishment of OAE-2. Significantly, emergence of the Caribbean plateau occurred synchronously to the beginning of its tectonic displacement between the Americas. We propose that this unusual volcanic and tectonic evolution led to drastic reduction of the flow of Pacific oxygenated bottom waters into the early Atlantic basin, leading to a series of regional anoxic events previously documented between the Coniacian and Santonian (OAE-3, ca. 89 to 84 Ma). In addition, emergence of the Caribbean Plateau in the early inter-American seaway could have facilitated migration of terrestrial organisms between the Americas in the Late Cretaceous. The formation of the Caribbean plateau had therefore a large range of possible environmental effects, from atmospheric to palaeo-oceanographic and biotic impacts

Autochthonous borderline tuberculoid leprosy in a man from Florida

Leprosy (Hansen's disease) is a chronic contagious granulomatous disease principally affecting the skin and peripheral nervous system, caused by Mycobacterium leprae. In this report, we present a case of autochthonous leprosy in a man from Florida as the first human case reported from this region. Authors believe dermatologists need to be aware of the possibility of autochthonous transmission of leprosy in the Eastern-Southern United States, and should consider leprosy in any patient with atypical skin lesions, even when a history of contact with armadillo is missing

Inclusión de futuros de energía eléctrica en portafolios de acciones

The purpose of this work is to measure the effect of including an electric power future contract in a portfolio of shares. The share price is modeled with a Multivariate Geometric Brownian Model, while the electricity futures model selected considers the short-term volatility of the market, the speed of reversion to the mean of the spot price and the long-term forward premium (difference between the expected stock price and the future price). This methodology is applied to a set of shares and a futures contract in the Colombian market. The results show that when including an electricity future contract in a portfolio of shares, movements of the efficient frontier of the portfolio are presented in the direction of risk reduction that do not necessarily imply a reduction in the expected return. In addition, it is observed that the lower volatility, the lower the speed of reversion to the mean and the lower the leverage level of the futures contract, the greater the contribution to portfolio diversification (lower risk for equal levels of expected profitability). On the other hand, the risk premium does not have a significant effect on the efficient frontier.El propósito de este trabajo es medir el efecto de incluir un contrato de futuros de energía eléctrica en un portafolio de acciones. Se modeliza el precio de las acciones con un Modelo Browniano Geométrico Multivariado, mientras que el modelo de futuros sobre energía eléctrica empleado considera la volatilidad de corto plazo del mercado, la velocidad de reversión a la media del precio spot y la prima forward de largo plazo (diferencia entre precio esperado de bolsa y el precio del futuro). Esta metodología se aplica a un conjunto de acciones y a un contrato de futuros del mercado colombiano. Los resultados muestran que al incluir un contrato de futuros de electricidad en un portafolio de acciones se presentan movimientos de la frontera eficiente del portafolio en la dirección de la reducción del riesgo que no necesariamente implican una reducción del rendimiento esperado. Además, se observa que a menor volatilidad, menor velocidad de reversión a la media y menor nivel de apalancamiento del contrato de futuro, mayor es el aporte a la diversificación del portafolio (menor riesgo para niveles iguales de rentabilidad esperada). Por otra parte, la prima de riesgo no tiene un efecto significativo sobre la frontera eficiente

Calidad de Vida Relacionada con la Salud en Un Grupo de Adolescentes de Medellín (Colombia): Asociación con Aspectos Sociodemográficos, Exceso de Peso u Obesidad y Actividad Física

El objetivo del estudio fue describir la calidad de vida relacionada con la salud (CVRS) y su asociación con aspectos sociodemográficos, el exceso de peso u obesidad y la actividad física (AF) en un grupo de adolescentes de la ciudad de Medellín (Colombia). Para evaluar dichas variables se aplicaron diferentes instrumentos a 399 participantes. Las dimensiones de la CVRS con mayores puntuaciones fueron Apoyo Social y Amigos y Estado de Ánimo y Sentimientos. Ser hombre, tener una menor edad, cursar primaria, tener padres con educación superior, pertenecer a estrato socioeconómico alto, no tener obesidad por porcentaje de grasa o perímetro abdominal y presentar un nivel alto de AF se relacionaron con una mejor CVRS

Effect of an intervention with physical exercise and nutritional guidance on the components of the metabolic syndrome among young people with overweight

ABSTRACT: Interventions with physical exercise and nutritional guidance show changes in overweight among young people suffering from the metabolic syndrome (MS); nevertheless, their characteristics and results vary. Objective: To assess the effect of an intervention with physical exercise and nutritional guidance on components of the MS among overweighted young people. Materials and methods: Longitudinal study with an assessment before and another after the intervention in nine young people aged 11 to 17 years. Anthropometric aspects, resting heart rate, peak oxygen consumption (VO2peak), insulinemia, HOMA, and components of the MS were assessed. Intervention consisted of 12 weeks of supervised exercise, three 90-minute sessions/week (aerobic and strength), plus two unsupervised sessions; the weekly supply of fruits and vegetables in order to cover the five recommended daily servings, and individual and group nutrition education. Results: With the intervention waist circumference decreased from 90.5 ± 11.0 to 88.1 ± 9.9 cm; BMI from 30.2 ± 5.8 to 29.3 ± 5.6 kg/m2 ; total body fat from 39.8 ± 13.0 to 34.3 ± 9.0%; glycemia from 86.0 ± 8.6 to 83.1 ± 5.0 mg/dL; insulinemia from 23.2 ± 9.8 to 19.4 ± 7.6 µU/mL; HOMA-IR from 2.89 ± 1.21 to 2.39 ± 0.93; resting heart rate from 87.9 ± 4.3 to 78.2 ± 5.5 rpm, and VO2peak increased from 36.3 ± 5.1 to 38.5 ± 4.1 mL/kg/min. Four out of six young people with the diagnosis of MS at the beginning of the study did not present it at the end. Conclusions: Participating in an exercise program and increase in the consumption of fruits and vegetables among overweighted young people with components of the MS produced positive modifications in body composition, VO2peak, resting heart rate, and glycemia, as well as in the components and prevalence of the MS.RESUMEN: Las intervenciones con ejercicio físico y orientación nutricional muestran cambios en el exceso de peso en jóvenes con el síndrome metabólico (SM); sin embargo, sus características y resultados son diversos. Objetivo: evaluar el efecto de una intervención con ejercicio físico y orientación nutricional sobre componentes del SM en jóvenes con exceso de peso. Materiales y métodos: estudio longitudinal con una evaluación antes y otra después, en nueve jóvenes entre 11 y 17 años. Se evaluaron aspectos antropométricos, frecuencia cardíaca en reposo (FCR), consumo pico de oxígeno (VO2pico), insulinemia, resistencia a la insulina (HOMA) y componentes de SM. La intervención consistió en 12 semanas de ejercicio supervisado, tres sesiones/semana de 90 minutos (aeróbico y de fuerza), más dos sesiones no supervisadas; el suministro semanal de frutas y verduras para cubrir las cinco porciones diarias recomendadas y educación nutricional individual y colectiva. Resultados: luego de la intervención disminuyeron la circunferencia de la cintura de 90,5 ± 11,0 a 88,1 ± 9,9 cm; el IMC de 30,2 ± 5,8 a 29,3 ± 5,6 kg/m2 ; la grasa corporal total de 39,8 ± 13,0 a 34,3 ± 9,0%; la glucemia de 86,0 ± 8,6 a 83,1 ± 5,0 mg/dL; la insulinemia de 23,2 ± 9,8 a 19,4 ± 7,6 µU/mL; el HOMA-IR de 2,89 ± 1,21 a 2,39 ± 0,93; la FCR de 87,9 ± 4,3 a 78,2 ± 5,5 bpm y aumentó el VO2pico de 36,3 ± 5,1 a 38,5 ± 4,1 mL/kg/min; de seis jóvenes con diagnóstico de SM al inicio, cuatro no lo presentaron al final. Conclusiones: participar en un programa de ejercicio y aumentar el consumo de frutas y verduras en los jóvenes con exceso de peso y componentes del SM generó modificaciones positivas en la composición corporal, el VO2pico, la FCR y la glucemia así como en los componentes y prevalencia del SM

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Clustering COVID-19 ARDS patients through the first days of ICU admission. An analysis of the CIBERESUCICOVID Cohort

Background Acute respiratory distress syndrome (ARDS) can be classified into sub-phenotypes according to different inflammatory/clinical status. Prognostic enrichment was achieved by grouping patients into hypoinflammatory or hyperinflammatory sub-phenotypes, even though the time of analysis may change the classification according to treatment response or disease evolution. We aimed to evaluate when patients can be clustered in more than 1 group, and how they may change the clustering of patients using data of baseline or day 3, and the prognosis of patients according to their evolution by changing or not the cluster.Methods Multicenter, observational prospective, and retrospective study of patients admitted due to ARDS related to COVID-19 infection in Spain. Patients were grouped according to a clustering mixed-type data algorithm (k-prototypes) using continuous and categorical readily available variables at baseline and day 3.Results Of 6205 patients, 3743 (60%) were included in the study. According to silhouette analysis, patients were grouped in two clusters. At baseline, 1402 (37%) patients were included in cluster 1 and 2341(63%) in cluster 2. On day 3, 1557(42%) patients were included in cluster 1 and 2086 (57%) in cluster 2. The patients included in cluster 2 were older and more frequently hypertensive and had a higher prevalence of shock, organ dysfunction, inflammatory biomarkers, and worst respiratory indexes at both time points. The 90-day mortality was higher in cluster 2 at both clustering processes (43.8% [n = 1025] versus 27.3% [n = 383] at baseline, and 49% [n = 1023] versus 20.6% [n = 321] on day 3). Four hundred and fifty-eight (33%) patients clustered in the first group were clustered in the second group on day 3. In contrast, 638 (27%) patients clustered in the second group were clustered in the first group on day 3.Conclusions During the first days, patients can be clustered into two groups and the process of clustering patients may change as they continue to evolve. This means that despite a vast majority of patients remaining in the same cluster, a minority reaching 33% of patients analyzed may be re-categorized into different clusters based on their progress. Such changes can significantly impact their prognosis