The transtheoretical model and obesity: a bibliometric study

The Transtheoretical Model of behaviour change is currently one of the most promising models in terms of understanding and promoting behaviour change related to the acquisition of healthy living habits. By means of a bibliographic search of papers adopting a TTM approach to obesity, the present bibliometric study enables the scientific output in this field to be evaluated. The results obtained reveal a growing interest in applying this model to both the treatment of obesity and its prevention. Otherwise, author and journal outputs fit the models proposed by Lotka and Bradford, respectively

A Simple Test of Momentum in Foreign Exchange Markets

This study proposes a new method for testing for the presence of momentum in nominal exchange rates, using a probabilistic approach. We illustrate our methodology estimating a binary response model using information on local currency / US dollar exchange rates of eight emerging economies. After controlling for important variables affecting the behavior of exchange rates in the short-run, we show evidence of exchange rate inertia; in other words, we find that exchange rate momentum is a common feature in this group of emerging economies, and thus foreign exchange traders participating in these markets are able to make excess returns by following technical analysis strategies. We find that the presence of momentum is asymmetric, being stronger in moments of currency depreciation than of appreciation. This behavior may be associated with central bank intervention.Momentum, foreign exchange markets, hazard duration analysis, emerging economies. Classification JEL: G14, G15, C41.

The Competing Risks of Acquiring and Being Acquired: Evidence from Colombia´s Financial Sector

This paper studies the determinants of the probability of participating in a process of merging or acquisition for financial institutions in Colombia. We use survival analysis techniques and competing risks models to estimate the probability of participating in such processes as an acquiring or acquired firm. Using an especially rich database containing financial information of Colombian banks for the period 1990 - 2007, we find that both macroeconomic and microeconomic variables are important determinants of such probability. However, there are differential effects for the acquiring firm and the acquired firm. Particularly, while firm size and solvency result significant determinants of the probability of being an acquiring firm, efficiency is an important determinant of the probability of being acquired. Also, the concentration index, that plays no role for acquiring firms, plays an important role in the probability of being acquired.Survival analysis; competing risk models; Colombia

The Cyclical Behavior of Bank Capital Buffers in an Emerging Economy: Size Does Matter

Using a panel of Colombian banks and quarterly data between 1996:1 and 2010:3, we study the relationship between short-run adjustments in bank capital buffers and the business cycle. We follow a partial adjustment framework and control for several variables that have been identified as important determinants of bank capital buffers in previous studies, and find that bank capital buffers vary over the business cycle. We are able to identify a negative co-movement of capital buffers and the business cycle. However, we also find that capital buffers of small and large banks behave asymmetrically during the business cycle. While the former appear to be constant over time, once the appropriate set of control variables is used, the latter present a countercyclical behavior. Our results suggest the possible need of the implementation of regulatory policy measures in developing countries.Bank capital buffers, Credit risk, Regulation, Colombia. Classification JEL: C26, G2, G28.

Contextual control of conditional discrimination of the own behavior in pigeons

An experiment in which a pigeon was trained in contextual discrimination of its own behavior was carried out. When the experimental chamber was illuminated with a constant light, the pigeon had to peck on a red (or green) key in the sample component after having been pecking to the left (or to the right). When the chamber was illuminated with an intermittent light, the reinforced sample-comparison sequences were the opposite. The subject learned the task in about 40 sessions and maintained high correct response ratios even though the reinforcement probability decreased from 1 to 0.2 after each correct trial. The results are discussed in terms of the kind of discriminative rule and the kind of hierarchic structure involved in the task.Se llevó a cabo un experimento en el que se entrenó a una paloma en una discriminación contextual de su propia conducta. Cuando estaba iluminada la luz general de la cámara experimental de manera constante, la paloma tenía que picar una tecla roja (o verde) tras haber estado picoteando a la izquierda (o derecha) en el componente de muestra. Cuando la luz general de la cámara se iluminaba de manera parpadeante, las secuencias reforzadas muestra-comparación fueron las contrarias. El sujeto aprendió la tarea en unas 40 sesiones y siguió manteniendo unos altos índices de acierto a pesar de bajar la probabilidad de reforzamiento tras cada ensayo correcto de 1 a 0.2. Los resultados se discuten en relación con el tipo de regla discriminativa y de estructura jerárquica involucradas en esta tarea