One‐inflation and unobserved heterogeneity in population size estimation by Ryan T. Godwin

In this study, we would like to show that the one‐inflated zero‐truncated negative binomial (OIZTNB) regression model can be easily implemented in R via built‐in functions when we use mean‐parameterization feature of negative binomial distribution to build OIZTNB regression model. From the practitioners' point of view, we believe that this approach presents a computationally convenient way for implementation of the OIZTNB regression model.     

Economic growth and environmental impacts: An analysis based on a composite index of environmental damage

The conflict between economic growth and the environment is complex and sharper today than ever before. Indeed, the relationship between economic growth and the sustainability of ecosystems has been extensively discussed in the literature, but the results remain controversial.This paper reviews the use of single and composite indicators of environmental damage and questions whether the Environmental Kuznets Curve (EKC) hypothesis sufficiently mirrors the relationship between economic growth and ecological damage. Ecological Indicators are relevant when they potentially inform society about ecological developments in a reliable way. We use the modified composite index of environmental performance (mCIEP) to measure environmental damage, and GDP per capita to represent economic growth. The econometric model is developed using panel data composed of 152 countries and a period of 6 years. The model is estimated for the full sample, for three different sets of countries, by level of development, and a decomposition analysis is carried out, which corresponds to the study of the CIEP individual dimensions.Our results reveal that, at present, the EKC hypothesis is not proved. We conclude that it is critical to be clear that economic growth alone is not enough to improve environmental quality. Therefore, creating a consistent, coherent and effective environmental policy framework is essential in order to improve environmental quality that supports wellbeing and enables long-term economic development.     

Analysis of data captured by an on-line image capture system from an analytical ultracentrifuge using schlieren optics

The recent development in this laboratory of an automated data capture system, for refractometric optics on the analytical ultracentrifuge has removed the requirement for tedious and time consuming manual acquisition which had led to a decline in the use of schlieren optics. At the same time this system has increased the amount of data easily available from such an optical system with maintained or increased precision. From the advent of such a system has arisen the need for a package to facilitate the analysis of these data and to extend the range of analytical methods used. Using the improved data sets now available has also enabled us to successfully use methods which have lapsed in popularity over the last two decades. We have also been able to successfully apply radial derivative methods (Bridgman 1942) which have not routinely been applied to the analysis of sedimentation velocity experiments using schlieren optics. In this paper we describe the methods we have so far used to analyse data and present results for previously well defined molecules to demonstrate that the results obtained are reliable. Received: 1 November 1996 / Accepted: 15 January 1997     

Climate and the evolution of skull metrics in man.

Two types of data, anthropometric and gene frequencies, may be used to reconstruct human evolution. Previous research, reconstructing the history of racial differentiation on the basis of gene frequencies, indicated that the major separation between human groups was that between Africans and Europeans on one side and peoples from Australia, East Asia and Americas on the other. A similar attempt by Howells ('73b), based on skull measurements in 17 ancient populations, in agreement with earlier anthropometric data, showed the major separation to be between Africans and Australians on one side and Europeans, Asians and Americans on the other. Climate could be a contributing factor to the observed differences in skull and anthropometric measurements. Howells' data showed high correlations with several climatic indicators. Carrying out the phylogenetic analysis after elimination by linear regression of the effects of climate has resolved to a great extent the discrepancy between anthropometric and gene frequency data.     

Delaying conservation actions for improved knowledge: how long should we wait?

Decisions about where conservation actions are implemented are based on incomplete knowledge about biodiversity. The Protea Atlas is a comprehensive database, containing information collated over a decade. Using this data set in a series of retrospective simulations, we compared the outcome from different scenarios of information gain, and habitat protection and loss, over a 20-year period. We assumed that there was no information on proteas at the beginning of the simulation but knowledge improved each year. Our aim was to find out how much time we should spend collecting data before protecting habitat when there is ongoing loss of habitat. We found that, in this case, surveying for more than 2 years rarely increased the effectiveness of conservation decisions in terms of representation of proteas in protected areas and retention within the landscape. If the delay is too long, it can sometimes be more effective just using a readily available habitat map. These results reveal the opportunity costs of delaying conservation action to improve knowledge.