Comparación de metodologías de optimización de carteras: Markowitz vs. Black-Litterman, para activos financieros colombianos

Personas naturales y compañías financieras que manejan grandes volúmenes de capital, especialmente fondos de pensiones y aseguradoras, deben tener muy claro tanto el nivel de exposición al riesgo como la rentabilidad esperada de las carteras de activos financieros que conforman para cada uno de sus clientes desde antes de que estos inviertan -- El presente trabajo busca contribuir en este sentido presentando las diferencias y las principales ventajas y desventajas de utilizar los métodos Markowitz y Black-Litterman, para optimizar carteras con activos del mercado de capital colombiano -- Dicha comparación se lleva a cabo mediante el cálculo de la frontera eficiente para cada uno de los métodos -- Los resultados muestran que el método Black-Litterman se ajusta más a las necesidades de diversificación de un inversionista que transa con activos colombiano

An Uphill Battle: The Relationship Between Geography and Terrorism

En cuanto al efecto de la geografía en el comportamiento socialmente violento, este estudio introduce la idea de que la fragmentación geográfica está asociada con más terrorismo, dada su cercana relación con el role del gobierno y las condiciones socioeconómicas de las personas. Nosotros consideramos un panel de 128 países entre 1971 y 2005 usando metodologías para datos de conteo. Esto nos permite proveer evidencia robusta de un efecto consistente, incluso cuando diferentes controles son incluidos. Nuestra estimación de referencia indica que un país 1% más geográficamente fragmentado es asociado con un incremento de 1.38 en el promedio de número de ataques terroristas.Regarding the effect of geography on social violent behavior, this study introduces the idea that Geographic Fragmentation is associated with more terrorism, given its close relationship with the role of the government and socioeconomic conditions of people. We consider a panel of 128 countries between 1971 and 2005 using count data methodologies. This allows us to provide robust evidence for a consistent effect, even when different controls are included. Our baseline estimate indicates that one country with a 1% higher measure of Geographic Fragmentation is associated with an increment of 1.38 in the number of terrorist attacks on average

Plan de negocios para la elaboración y comercialización de amoblamiento sustentable a partir de material recuperado

La gestión de residuos sólidos se ha convertido en uno de los temas más importantes en la gestión ambiental del siglo XXI, especialmente de los residuos que presentan mayor complejidad a la hora de su manejo por su baja capacidad para degradarse. Las llantas son uno de esos residuos, estas presentan una estructura compleja, formada por diversos materiales como caucho, acero y tejido de poliamida o poliéster. La separación de estos materiales en sus componentes originales es un proceso difícil, por lo que el reciclaje de las llantas usadas se ha orientado mayormente a su aprovechamiento en conjunto. El presente trabajo de grado pretende generar un plan de negocios para la elaboración y comercialización de amoblamiento sustentable, utilizando este tipo de residuos

Dynamics of larval fish and zooplankton in selected south and west coast estuaries of South Africa

Larval fish and zooplankton assemblages were studied in nine south and west coast estuaries in the cool-temperate and the cool/warm-temperate boundary region between June 2003 and March 2004. This study served to provide new information on previously unstudied estuaries and expand on existing knowledge of larval fish and zooplankton assemblages associated with various estuary types. The south and west coast estuaries sampled in this study showed lower salinities (12.2 - 13.7), lower water temperatures (14.5 - 16.9 °C) and higher turbidities (k = 0.02 - 0.04) in winter and spring while higher salinities (21.7 - 21.8), higher water temperatures (21.7 - 23.1°C) and lower turbidities (k 20 orders and >35 families. The copepod Pseudodiaptomus hessei dominated (59 %) the zooplankton and occurred in similar densities to those observed in other South African estuaries. Larval fish and zooplankton varied across seasons, peaking simultaneously in summer although zooplankton showed additional density peaks during the closed phase of some estuaries. Both plankton components were more abundant in the oligohaline and mesohaline zones within the estuaries. Freshwater input, estuary type and the biogeography of the area influenced the composition and structure of larval fish and zooplankton assemblages in these estuaries. The findings suggest that the estuaries are functioning as successful breeding areas for the larvae of endemic estuary-resident fish species and that these estuaries have to be managed to ensure an adequate freshwater supply to maintain the biological integrity of the ecosystem, specially the maintenance of the highly productive River-Estuary Interface (REI) regions

Ecological genetic connectivity between and within southeast African marginal coral reefs.

Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2014.Marine protected areas (MPAs) have been established along the East African coast to protect coral communities from human and natural disturbance. Their success is dependent on the degree to which resource populations are self-seeding or otherwise connected. Estimates of contemporary gene flow on or between south-east African reefs are thus required to reveal the interdependence of the South African coral communities and those to the north. Accordingly, the ecologically relevant (1 or 2 generations) connectivity of two broadcast-spawning corals, Acropora austera and Platygyra daedalea, was assessed on reefs in the region, from the Chagos Archipelago to Bazaruto Island in Mozambique and Sodwana Bay in South Africa, using hyper-variable genetic markers. Analysis of genetic diversity and differentiation provided evidence for the existence of four discrete genetic populations of A. austera and five of P. daedalea in the sampled area. Higher genetic diversity was found on northern South African reefs (Nine-mile Reef and Rabbit Rock) and migration patterns inferred from assignment tests suggested that, at ecological time scales, South African reefs are disconnected from those in Mozambique and might originate from a source of gene flow that was not sampled. The analysis of fine-scale genetic connectivity conducted on Two-mile Reef (TMR) demonstrated the existence of significant spatial genetic structure at the reefal scale that might be related to the non-random dispersal of coral larvae, putatively explaining the genetic discontinuity observed in the region. Altogether, the results are consistent with the isolation observed in other studies using less variable markers, and support the hypothesis that there is demographic discontinuity between the coral populations along the south-east African coast. More importantly, Acropora austera and P. daedalea represent different life strategies in the South African reef communities yet manifested similar genetic patterns, suggesting that these corals are responding similarly to forces that are driving genetic connectivity in the region. For management purposes, the genetically distinct populations identified at each of the spatial scales analysed in this study may correspond to management units, or evolutionarily significant units. Furthermore, since some reefs appear to act as “landing-sites” for migrants (Nine-mile Reef) and there is evidence of significant within-reef genetic structure (TMR), an adaptive management framework would be the best option for the MPA in the region

South-habitat. a journey through autogenerated settlements of the andean territory

This article presents the summary of the document written to achieve an Architect degree at the National University of Colombia in 2006, thesis tutored by the geographer Anne Catherine Chardon: [HABITATSUR] SOUTHHABITAT. A Journey through Autogenerated Settlements of the Andean Territory. The work presents the results of a research that studies four cases; four cities constructed beyond official planning, located in the Andean cities of La Paz (Bolivia), Cuzco (Peru), Quito (Ecuador) and Manizales (Colombia). This research is conceived under the perspective of the habitat as a central concept, thus, a dissertation on this concept is made among the implications and the employment of it in planning and construction of cities. From the theorization on the term is set a reflection on the inequality and the segregation that Latin American and Andean cities impose to its inhabitants. Finally, auto-generated settlement is proposed as a concept to study these phenomena from its own formal, social and historical characteristics. Under this perspective, the research proposes a methodology that establishes two moments of analysis: the formation and the transformation of the settlement. At every moment two processes are analyzed: the appropriation, focused in the construction of the house and the relations of the home with the neighborhood; and the “territorialización”, focused in the physical-space and social organization of the neighborhood, and in its relations with the city and the State. These processes are analyzed under variables of legality, space type, sociality and aesthetics, soon to make a comparative study between the studied cities, differentiating between the capital and intermediate cities. Finally there is a dissertation on the ways that from architecture and the academy, could be proposed and improved the Latin American urban habitat.El artículo presenta la síntesis del trabajo de grado HABITATSUR. Un recorrido por los asentamientos autogenerados del territorio andino, dirigido por la geógrafa Anne Catherine Chardon y presentado para optar al título de arquitecto por la Universidad Nacional de Colombia, sede Manizales, en el año 2006. El trabajo presenta una investigación que toma como estudio de caso cuatro asentamientos humanos construidos por fuera de la planificación oficial, los cuales están ubicados en las ciudades andinas de La Paz (Bolivia), Cuzco (Perú), Quito (Ecuador) y Manizales (Colombia). Dicha investigación se plantea bajo la perspectiva del hábitat, por lo cual se realiza una amplia disertación sobre este concepto y sobre las implicaciones que tiene su uso en la planificación y construcción de las ciudades. A partir de la definición de hábitat, se propone una reflexión sobre la inequidad y la segregación de la ciudad latinoamericana y andina en particular. Finalmente, se propone el concepto de asentamientos autogenerados como una forma de estudiar dichos fenómenos desde sus propias características formales, sociales e históricas. Bajo esta perspectiva, el estudio realizado en cuatro barrios andinos propone una metodología que establece dos momentos de análisis: la formación del asentamiento y su transformación. En cada momento se analizan dos procesos: la apropiación, enfocada en la construcción de la casa y las relaciones del hogar con el barrio, y la territorialización, enfocada en la organización físico-espacial y social del barrio, y en sus relaciones con la ciudad y con el Estado. Dichos procesos son analizados bajo variables de tipo legal, espacial, sociales y estéticas, para luego hacer un estudio comparativo entre las ciudades estudiadas, diferenciando entre las ciudades capitales e intermedias. Por último, se reflexiona sobre las formas como, desde la arquitectura y la academia, se podría proponer y mejorar el hábitat urbano latinoamericano

Efficient and Robust Approaches for Analysis of SMARTs: Illustration using the ADAPT-R Trial

Personalized intervention strategies, in particular those that modify treatment based on a participant's own response, are a core component of precision medicine approaches. Sequential Multiple Assignment Randomized Trials (SMARTs) are growing in popularity and are specifically designed to facilitate the evaluation of sequential adaptive strategies, in particular those embedded within the SMART. Advances in efficient estimation approaches that are able to incorporate machine learning while retaining valid inference can allow for more precise estimates of the effectiveness of these embedded regimes. However, to the best of our knowledge, such approaches have not yet been applied as the primary analysis in SMART trials. In this paper, we present a robust and efficient approach using Targeted Maximum Likelihood Estimation (TMLE) for estimating and contrasting expected outcomes under the dynamic regimes embedded in a SMART, together with generating simultaneous confidence intervals for the resulting estimates. We contrast this method with two alternatives (G-computation and Inverse Probability Weighting estimators). The precision gains and robust inference achievable through the use of TMLE to evaluate the effects of embedded regimes are illustrated using both outcome-blind simulations and a real data analysis from the Adaptive Strategies for Preventing and Treating Lapses of Retention in HIV Care (ADAPT-R) trial (NCT02338739), a SMART with a primary aim of identifying strategies to improve retention in HIV care among people living with HIV in sub-Saharan Africa

Tabla de conversión de unidades

En este manual se han recopilado las constantes universales, electromagnéticas, atómicas y nucleares y físico-químicas más importantes, además de una completa tabla de conversiones en la que se dan las fórmulas para la conversión de temperaturas y un diagrama de Mollier (entalpía-entropía para el vapor de agua), entre otros datos, además, se presenta como producto parcial del proyecto de investigación P09246, producción de jabón y alcohol en gel, mejorados en su poder bactericida para prevenir contagios con posibles virus y/o bacterias en el ITM

Triple combination of insulin glargine, sitagliptin and metformin in type 2 diabetes : the EASIE post-hoc analysis and extension trial

Q3Q1Aim We examined the effects of adding glargine to metformin–sitagliptin (MS + G) or sitagliptin to metformin–glargine (MG + S) therapy in type 2 diabetic persons uncontrolled after 24-week MS or MG dual therapy. Methods Subjects with A1c ≥ 7% on MS or MG treatment were respectively given glargine (0.2 U/kg starting dose) or sitagliptin (100 mg daily) for 12 weeks. The primary endpoint was number of subjects attaining A1c goal defined as < 7%. Results After receiving 24-week MS or MG dual therapy in the original EASIE Study, 42% (104/248) on MS and 68% (152/224) on MG attained A1c < 7% (p < 0.0001). The reduction in A1c was negatively associated with baseline fasting blood glucose (FBG) only in the MG group. Reduction in A1c was not related to baseline postprandial blood glucose (PPBG) in either the MG or MS group. Amongst 194 eligible patients, 57.7% (n = 111) entered the 12-week extension trial [MS + G:74/131, 57.3%; MG + S:37/63, 58.7%) with 55 (51.9%) subjects attaining goal [MS + G:59.2%; MG + S:37.1%] at week 12. The final insulin dosage was similar in both groups [MS + G: 0.46 U/kg; MG + S: 0.45 U/kg] with a higher rate of hypoglycemia in the MG + S (6.5 events/patient-year) than the MS + G group (3.2 events/patient-year), although neither group had severe hypoglycemia. Conclusion In metformin-treated type 2 diabetes patients, high fasting BG predicted greater A1c reductions with the addition of glargine, but not with sitagliptin. In subjects uncontrolled with 6-month dual therapy of MS or MG, 50% attained A1c < 7% with triple therapy of MS + G or MG + S in 12 weeks. The increased rate of hypoglycemia with MG + S (but not with MS + G) underlines the need to take measures to avoid the hypoglycemia