Improving the Measurement of Core Inflation in Colombia Using Asymmetric Trimmed Means

The study evaluates the virtues of asymmetric trimmed means as efficient estimators of core inflation for Colombia, an economy with high and variable inflation rates. Results suggest that the proposed indicators are more efficient than alternative indexes and are particularly suited for environments where price change distributions are non-normal. Computations indicate that an optimally trimmed estimator for the 27-component Colombian CPI during the 1972:06 to 1997: 12 period requires that 12 percent be trimmed from the upper tail and 24 percent from the lower tail. This indicator exhibits substantially higher efficiency than the weighted average of price changes (i-e.,CPI inflation), the CPI excluding food and energy, the median and symmetric trimmmed means. These findings are robust to changes in the 36-month centered moving average benchmarck of annual inflation. the medain and symmmetric trimmed means. These findings are robust changes in the 36-month centerd moving average benchmark of annual inflation. The optimal estimator is not found to be robust to changes in data sample. This is likely due to changes in parameters of the underying data distribution due to structural changes in the Colombian economy, particularly in the post-1990 period. Optimal levels of asymmetrical trimming are also found to be highly sensitive to the degree of disaggregation of the CPI data. This is expected since greater disaggregation reveals higher kurtosis and skewness of the underying data. The CPI excluding food and energy and the median do not seem to provide persistent efficiency gaings in estimation of inflation with respect to the weighted mean. Food and energy prices are critical sectors of middle income economies such as Colombia and contain valuable information about medium and long-term trends in inflation. Finally, the median excludes many prices-especially those in the upper tail- that seem to contain valuable information about long-term trends in inflation.

Price Behavior in an Inflationary Environment: Evidence from Supermarket Data

This paper analyzes several important aspects of price behavior using disaggregated weekly data on prices of supermarket products in Colombia between 1991 and 1994. The analysis shows that despite hight and persistent rates of inflation in the economy, price quotations persist on average for two months. The large proportion of observations for which stores opt not to change prices highlight the importance of menu costs, even in an economy accustomed to persistent double-digit inflation. Despite the seemingly hight levels of rigidity, the degree of real price erosion found before prices change are lower than those found in other inflationary economies. Price declines are not uncommon, and downward rigidity does not seem to be an issue in the Colombian inflationary environment. Aggregate price changes are also found to exert an important effect on relative price variation at the aggregate and commodity level.

THE LINK BETWEEN FARMGATE AND WORLD PRICES IN THE WAKE OF TRADE LIBERALIZATION: THE CASE OF COLOMBIA

The study measures the extent to which farmgate price levels have effectively increased their degree of integration with world price movements following trade liberalization in Columbia. Results show that the extent of integration varies greatly depending upon the crop, and that market-specific policies have isolated some farmers from international influences.Demand and Price Analysis, International Relations/Trade, Marketing,

Risk, Concentration and Market Power in the Banking Industry: Evidence from the Colombian System (1997-2006)

This paper examines the relationship between risk, concentration and the exercise of market power by banking institutions. We use monthly balance-sheet and interest rate data for the Colombian banking system from 1997 to 2006. The evidence shows that, in the face of high risk, banks transfer a larger share of risk to customers through higher intermediation margins. The result suggests that systemic risk acts as a collusion" device for banks: while high concentration is not enough to have collusion, the true effects of high market concentration on interest rates´ mark-ups emerge when the system is under stress."Banking, market power, risk, concentration, intermediation margins

Reviving keV sterile Neutrino Dark Matter

We propose a new production mechanism for keV sterile neutrino dark matter which relies neither on the oscillations between sterile and active neutrinos nor on the decay of additional heavier particles. The dark matter neutrinos are instead produced by thermal freeze-out, much like a typical WIMP. The challenge consists in balancing a large Yukawa coupling so that the sterile neutrinos thermalize in the early universe on the one hand, and a small enough Yukawa coupling such that they are stable on cosmological scales on the other. We solve this problem by implementing varying Yukawa couplings. We achieve this by using a three-sterile neutrino seesaw extension to the SM and embedding it in a Froggatt-Nielsen model with a single flavon. Because the vev of the flavon changes during the electroweak phase transition, the effective Yukawa couplings of the fermions have different values before and after the phase transition, thus allowing for successful dark matter genesis. Additionally, the hierarchy in the flavour structure is alleviated and the origin of the light neutrino masses are explained by the interplay of the seesaw and Froggatt-Nielsen mechanisms.Comment: 17 page

Una utopía, factor esencial en la formación como educador matemático

Las autoridades educativas, regionales, nacionales e internacionales, además, profesores, padres de familia, entre otros, se encuentran actualmente preocupados por el bajo rendimiento en matemáticas y la alta deserción de los alumnos en esta disciplina. El sistema educativo debe responder acertadamente a los retos de la formación de mentes racionales, discursivas, reflexivas y críticas que puedan asumir el desarrollo de las ciencias y la tecnología moderna, que si bien es cierto pueden mejorar la calidad de vida de la sociedad, también pueden deteriorarla

Are Time-Domain Self-Force Calculations Contaminated by Jost Solutions?

The calculation of the self force in the modeling of the gravitational-wave emission from extreme-mass-ratio binaries is a challenging task. Here we address the question of the possible emergence of a persistent spurious solution in time-domain schemes, referred to as a {\em Jost junk solution} in the literature, that may contaminate self force calculations. Previous studies suggested that Jost solutions are due to the use of zero initial data, which is inconsistent with the singular sources associated with the small object, described as a point mass. However, in this work we show that the specific origin is an inconsistency in the translation of the singular sources into jump conditions. More importantly, we identify the correct implementation of the sources at late times as the sufficient condition guaranteeing the absence of Jost junk solutions.Comment: RevTeX. 5 pages, 2 figures. Version updated to match the contents of the published articl

Aproximación de curvas en R^2 y R^3 a partir del plegado de superficies planas

El carácter discreto y continuo de las matemáticas se pone en evidencia al generar algunos tipos de curvas en y por medio del doblado de papel. Esta actividad hace que el concepto de Suma de Riemann, en el que se encuentra encubierto el concepto de infinito y los métodos clásicos para hallar el área bajo ciertas curvas, pueda fundamentarse y visualizarse a través de la axiomática de Huzita-Hatori formulando otra perspectiva en la iniciación al estudio del cálculo diferencial e integral

La caducidad en los actos de determinación de la obligación tributaria de la administración y su tratamiento en la legislación ecuatoriana

Este artículo trata sobre la caducidad de la facultad determinadora de la obligación tributaria de la administración, con particular referencia a la ejercida de oficio o de modalidad mixta, conlleva el análisis previo de esta figura frente a la prescripción, a la luz del Código Tributario ecuatoriano, con respaldo en reconocida producción doctrinaria, dejando al descubierto la falta de previsión legal sobre los plazos de caducidad que deben obrar en el ejercicio de esa facultad y la incidencia por su omisión.The article deals with the caducity of the determination faculty of tax administrations, with particular reference to the official determination and the mixed determination. The study starts by differencing caducity and prescription, in light of the ecuadorian Tax Code, and supported by recognized authors. The article demonstrates that there is a lack of legal prevision in regard to caducity terms, and discusses the incidence of this legal omission