Interpreting spotted dolphin age distributions

Previous work has determined the age distribution from a sample of spotted dolphins (Stenella attenuata) killed in the eastern Pacific tuna purse-seine fishery. In this paper we examine the usefulness of this age distribution for estimating natural mortality rates. The observed age distribution has a deficiency of individuals from 5-15 years and cannot represent a stable age distribution. Sampling bias and errors in age interpretation are examined as possible causes of the "dip" in the observed age structure. Natural mortality rates are estimated for the 15+ age classes based on the assumption that these are sampled representatively. The resulting annual survival rate <D.82) is too low to allow population growth, given what is known about dolphin reproductive rates. (PDF contains 30 pages.

Age Distribution, Saving and Consumption in Sweden

This paper focuses on an empirical analysis of the dependency between age structure and aggregate consumption and the composition of aggregate savings. In a long-run consumption function of life cycle type, different demographic variables have a conclusive, statistically significant effect. In investigating the link between demographic variables and the composition of aggregate savings, a simple simultaneous model is used, and a saving function and a house price equation are estimated. The result even here is that age composition matters for house price and savings. This conclusion is also made visible by a simulation experiment. Finally is the model used to ascertain the effect on the recent Swedish tax reform on savings.

Age distribution among NASA scientists and engineers

The loss of technical expertise through attrition in NASA and the aerospace industry is discussed. This report documents historical age-related information for scientific and engineering personnel in general and the NASA Lewis Research Center in particular, for 1968 through 1987. Recommendations are made to promote discussion and to establish the groundwork for action

Age Structure, Income Distribution And Economic Growth

economic policy; fiscal policy

Gaze Distribution Analysis and Saliency Prediction Across Age Groups

Knowledge of the human visual system helps to develop better computational models of visual attention. State-of-the-art models have been developed to mimic the visual attention system of young adults that, however, largely ignore the variations that occur with age. In this paper, we investigated how visual scene processing changes with age and we propose an age-adapted framework that helps to develop a computational model that can predict saliency across different age groups. Our analysis uncovers how the explorativeness of an observer varies with age, how well saliency maps of an age group agree with fixation points of observers from the same or different age groups, and how age influences the center bias. We analyzed the eye movement behavior of 82 observers belonging to four age groups while they explored visual scenes. Explorativeness was quantified in terms of the entropy of a saliency map, and area under the curve (AUC) metrics was used to quantify the agreement analysis and the center bias. These results were used to develop age adapted saliency models. Our results suggest that the proposed age-adapted saliency model outperforms existing saliency models in predicting the regions of interest across age groups

Extragalactic Globular Clusters in the Near-Infrared: V. IC 4051 and NGC 3311

We present the results of combined optical and near-infrared photometry for the globular cluster systems of the giant ellipticals IC 4051 and NGC 3311. We use the reduced age-metallicity degeneracy in (V-I) vs.(V-H) color-color diagrams to derive the cumulative age distribution within the red sub-population of globular clusters and to search for age sub-populations. The age distribution is then compared to the one determined for simulated globular cluster systems in order to set constraints on the relative age and size of these globular cluster sub-populations. In both galaxies we find a significant fraction of globular clusters with ages between 2- 5 Gyr. We also investigate the metallicity distribution in both systems. Small number statistics prevent us from making any definite statements concerning NGC 3311, but we find that the derived metallicity distribution of the IC 4051 clusters strongly depends on the assumed age distribution. Based on our most likely result that finds a large number of young/intermediate age clusters (~2 Gyr) within the selected globular cluster sample, we find metallicity peaks at $\sim$ -0.2 for the old clusters and +0.8 for the young clusters. Only few very metal poor clusters are found. However, the metallicity distribution within the young/intermediate globular cluster population is significantly affected by our choice of the applied Single Stellar Population model. The mean metallicity of the second generation of globular clusters changes from the above mentioned and extremely high +0.8 dex to +0.2 dex. Note that the model dependency becomes less severe with an increasing age of the cluster population.Comment: 21 pages, 21 figures, A&A, accepte