The role of woodpeckers (family: Picidae) as ecosystem engineers in urban parks: a case study in the city of Madrid (Spain)

Urban Ecosystems - Many species of the family Picidae, such as the woodpeckers, excavate the tree-cavities where they nest. Frequently the cavities are used during a single breeding season and...     

Behavioural determinants of perceived managerial and leadership effectiveness in Argentina

The purpose of this empirical study was to explore the perceptions of Argentinean managers and non-managerial employees about managerial and leadership effectiveness, and the extent to which the findings are generalized to other countries. The central research question addressed was as follows: How do people employed in Argentinean companies behaviourally distinguish effective managers from ineffective managers, and to what extent are the findings culture-specific or context-general? A total of 42 employees from private and public sector organizations in Cordoba, Argentina, were interviewed using critical incident technique. The interviews generated 302 critical incidents of which 155 were examples of positive (effective) managerial behaviour, and 147 of negative (ineffective) managerial behaviour. The findings suggest that Argentineans perceive as effective those managers who are supportive, considerate, motivating, caring, good decision makers, approachable, participative, fair-minded, communicative, actively involved, and who act as role models. This challenges the widely held belief that Argentineans prefer authoritarian managers over democratic ones.     

Human Capital,Trade Openness and Growth in Argentina in the 20th Century

We estimate a production function that accounts for the economic performance of the country in the 20th century. We elaborate long term time series whereas most of the recent empirical studies on growth are based on cross section analysis. This approach allows us to follow the various regime changes that can be identified in the rich economic history of Argentina. To evaluate Total Factor Productivity (TFP) we initially test the classical Solow Model. We estimate the speed of convergence of TFP and obtain a non convergence result. This speed of convergence has declined since the 1930s, and we find a phenomenon of divergence in the period 1970–90. We then analyse the impact on production of additional variables recently highlighted in the endogenous growth literature such as the process of catch up of foreign technical progress, human capital and trade openness. Chow tests for this extended production function give us a strong probability of changes in the growth regimes. The estimation, that takes into consideration the break points identified, shows that the impact of trade openness and foreign technology is not stable throughout the century. In what concerns the impact of education on economic growth, we find a strong effect of primary education on growth, and a weaker effect of secondary-university education.     

A Bayesian analysis for the Block and Basu bivariate exponential distribution in the presence of covariates and censored data

In this paper, we introduce a Bayesian Analysis for the Block and Basu bivariate exponential distribution using Markov Chain Monte Carlo (MCMC) methods and considering lifetimes in presence of covariates and censored data. Posterior summaries of interest are obtained using the popular WinBUGS software. Numerical illustrations are introduced considering a medical data set related to the recurrence times of infection for kidney patients and a medical data set related to bone marrow transplantation for leukemia.     

Recall searching with and without recall

We revisit the sequential search problem by Hey (J Econ Behav Organ 8:137–144, 1987). In a 2 \(\times \) 2 factorial design, varying fixed and random cost treatments with and without recall, we address open research questions that were originally stated by Hey (1987). Our results provide clear evidence for Hey’s (1987) conjecture that recall negatively affects performance in sequential search. With experience, however, search behavior with and without recall converges toward the optimal reservation rule. We further find that the utilization of optimal reservation rules is independent from the stochastic nature of the search cost.     

On the Exact and Near-Exact Distributions of the Product of Generalized Gamma Random Variables and the Generalized Variance

In this article, the authors first obtain the exact distribution of the logarithm of the product of independent generalized Gamma r.v.’s (random variables) in the form of a Generalized Integer Gamma distribution of infinite depth, where all the rate and shape parameters are well identified. Then, by a routine transformation, simple and manageable expressions for the exact distribution of the product of independent generalized Gamma r.v.’s are derived. The method used also enables us to obtain quite easily very accurate, manageable and simple near-exact distributions in the form of Generalized Near-Integer Gamma distributions. Numerical studies are carried out to assess the precision of different approximations to the exact distribution and they show the high accuracy of the approximations provided by the near-exact distributions. As particular cases of the exact distributions obtained we have the distribution of the product of independent Gamma, Weibull, Frechet, Maxwell-Boltzman, Half-Normal, Rayleigh, and Exponential distributions, as well as the exact distribution of the generalized variance, the exact distribution of discriminants or Vandermonde determinants and the exact distribution of any linear combination of generalized Gumbel distributions, as well as yet the distribution of the product of any power of the absolute value of independent Normal r.v.’s.     

A distance-based model for spatial prediction using radial basis functions

In the context of local interpolators, radial basis functions (RBFs) are known to reduce the computational time by using a subset of the data for prediction purposes. In this paper, we propose a new distance-based spatial RBFs method which allows modeling spatial continuous random variables. The trend is incorporated into a RBF according to a detrending procedure with mixed variables, among which we may have categorical variables. In order to evaluate the efficiency of the proposed method, a simulation study is carried out for a variety of practical scenarios for five distinct RBFs, incorporating principal coordinates. Finally, the proposed method is illustrated with an application of prediction of calcium concentration measured at a depth of 0–20 cm in Brazil, selecting the smoothing parameter by cross-validation.     

Estimating Age: College Males Versus Convicted Male Child Sex Offenders

Two samples, male college students and convicted male child sex offenders, are compared on their abilities to accurately estimate the age group of a series of photographs of a sole female ranging in age from 11 to 29. Both samples tend to overestimate the age group of the subject photos, and no significant difference was found between college students and convicted child sex offenders in their ability to estimate the age of females. Both groups are compared demographically, and only limited differences were found. The implications are discussed in regard to theory and prevention of child sexual abuse.