Asymptotically conical Ricci-flat Kahler metrics with cone singularities

The main result proved in this thesis is an existence theorem for asymptotically conical Ricci-flat Kahler metrics on C2 with cone singularities along a smooth complex curve. These metrics are expected to arise as blow-up limits of non-collapsed sequences of Kahler-Einstein metrics with cone singularities.Open Acces

Evaluating alternative methods for testing asset pricing models with historical data

We follow the correct Jagannathan and Wang (2002) framework for comparing the estimates and specification tests of the classical Beta and Stochastic Discount Factor/Generalized Method of Moments (SDF/GMM) methods. We extend previous studies by considering not only single but also multifactor models, and by taking into account some of the prescriptions for improving empirical tests suggested by Lewellen, Nagel and Shanken (2009). Our results reveal that SDF/GMM first-stage estimators lead to lower pricing errors than OLS, while SDF/GMM second-stage estimators display higher pricing errors than the classical Beta GLS method. While Jagannathan and Wang (2002), and Cochrane (2005) conclude that there are no differences when estimating and testing by the Beta and SDF/GMM methods for the CAPM, we show that their conclusion can not be extensible for multifactor models. Moreover, the Beta method (OLS and GLS) seem to dominate the SDF/GMM (first and second-stage) procedure in terms of estimators’ properties. These results are consistent across benchmark portfolios and sample periods.Beta Pricing Models; Stochastic Discount Factor; Pricing Errors; Evaluation of Factor Models.

The socle of a Leavitt path algebra

In this paper we characterize the minimal left ideals of a Leavitt path algebra as those ones which are isomorphic to principal left ideals generated by line point vertices, that is, by vertices whose trees do not contain neither bifurcations nor closed paths. Moreover, we show that the socle of a Leavitt path algebra is the two-sided ideal generated by these line point vertices. This characterization allows us to compute the socle of some algebras that arise as the Leavitt path algebra of some row-finite graphs. A complete description of the socle of a Leavitt path algebra is given: it is a locally matricial algebra.Comment: 13 pg

Mixidad socioespacial y gentrificación en la Ciudad Autónoma de Buenos Aires 1991-2010: Una aproximación cuantitativa a partir de datos censales

El artículo explora la mixidad socioeconómica y la gentrificación en la Ciudad Autónoma de Buenos Aires a partir de información censal de los años 1991, 2001 y 2010, buscando cuantificar dichos fenómenos y conocer sus tendencias recientes. Entre las conclusiones se destaca que la mixidad socioeconómica es un fenómeno que tiende a decrecer en la ciudad y que, en gran medida, es de tipo transitoria, producto de su estrecho vínculo con procesos de gentrificación que la tienen como un estadio intermedio entre el comienzo de la gentrificación y la etapa en que alcanza un grado mayor de desarrollo.This paper explores socioeconomic mixture and gentrification in Buenos Aires City based on census data from 1991, 2001 and 2010 censuses, seeking to determine the magnitude and trends of these particular urban phenomena. Conclusions suggest that socioeconomic mixture is mainly transitory and related to gentrification processes as an intermediate phase.Fil: Rodriguez, Gonzalo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Estudios Urbanos y Regionales; Argentin

On innocent victims and demons in Argentina (1983-1985)

On 24 March 1976 began the so-called "Process of National Reorganisation" (Proceso de Reorganización Nacional). This dictatorship, the last in Argentina's history, marked a turning point, distinguishing itself from preceding dictatorships by waging terror and carrying out forced disappearances. The Proceso established an organised, covert structure for kidnapping individuals who were considered "subversive", imprisoning them in clandestine prisons, torturing and murdering them. To this day, los desaparecidos (the disappeared) have remained hidden from the rest of the world because those responsible, with support from the state, secretly disposed of the corpses. According to the report by the National Commission on the Disappearance of Persons (CONADEP in Spanish), the number of desaparecidos totaled approximately 9 000 victims.Fil: Martin, Lucas Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentin

Variability of radiation use efficiency in mixed pastures under varying resource availability, defoliation and time scale

Forage productivity is the product between incident radiation, the fraction of radiation absorbed by the canopy (fAPAR) and radiation use efficiency (RUE). The extent to which forage productivity may be estimated through remote sensing depends on the relative effects of stress and defoliation on fAPAR and RUE. In a mixed pasture, we determined the relative impact of resource availability and defoliation on forage productivity, fAPAR and RUE, and we evaluated the impact of time scale on fAPAR and RUE under stress conditions. We conducted a one-year experiment in a temperate-mixed pasture subjected to different resource availability treatments and defoliation management. We measured RUE and fAPAR with different temporal windows. RUE was less responsive than fAPAR to changes in resource availability and defoliation intensity. However, RUE slightly decreased under water stress and increased under severe defoliation. Additionally, RUE variability during regrowth and among treatments depended on the temporal scale of observation: RUE was more variable for 12-day periods than 45- or 90-day periods. Our results reinforce the value of fAPAR as an explanatory variable of the variations in forage productivity due to changes in resource availability and management. In addition, the temporal scale of observation affects RUE variability. Thus, most variations of forage productivity may be captured by monitoring systems based on remote sensing of fAPAR provided that the time scale is coarse enough. However, the contrasting response of RUE and fAPAR to defoliation indicates a potential weakness of such a system when situations with contrasting defoliation regime are compared.Fil: Grigera, Gonzalo. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Oesterheld, Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Field trials of an improved cost-effective device for detecting peridomestic populations of Triatoma infestans (Hemiptera: Reduviidae) in rural Argentina

An improved device for detecting peridomestic Triatoma infestans consisting of one-liter recycled Tetra Brik milk boxes with a central structure was tested using a matched-pair study design in two rural areas in Argentina. In Olta (La Rioja), the boxes were installed beneath the thatched roofs and on the vertical wooden posts of each peridomestic structure. After a 5-month exposure, at least one of the recovered boxes detected 88% of the 24 T. infestans-positive sites, and 86% of the 7 negative sites by timed manual collections at baseline. In Amamá (Santiago del Estero), the boxes were paired with the best performing prototype tested before (shelter unit). After 3 months, some evidence of infestation was detected in 89% (boxes) and 79% (shelters) of 18-19 sites positive by timed collections, whereas 19% and 16% of 32 negative sites were positive, respectively. Neither device differed significantly in the qualitative or quantitative collection of every sign of infestation. The installation site did not modify significantly the boxes' sampling efficiency in both study areas. As the total cost of each box was half as expensive as each shelter unit, the boxes are thus the most cost-effective and easy-to-use tool for detecting peridomestic T. infestans currently available.Fil: Vazquez Prokopec, Gonzalo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Ceballos, Leonardo A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Salomón, Oscar Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Dirección Nacional de Institutos de Investigación. Administración Nacional de Laboratorios e Institutos de Salud. Centro Nacional de Diagnóstico e Investigaciones Endemo-epidémicas; ArgentinaFil: Gurtler, Ricardo Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentin