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  • Author or Editor: M. Baran x
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Abstract  

We define two closure operators of some well-known topological categories and investigate the relationships between these closure operators and the one that is given in [9]. As a consequence, we characterize separation properties T 0, T 1, and T 2 for these well-known categories and compare them with the ones that are given in [3] and [6]. Finally, we characterize the epimorphisms in the subcategories of these given categories.

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A modified version of the popular Lee-Carter method (Lee-Carter 1992) is applied to forecast mortality rates in Hungary for the period 2004–2040 on the basis of mortality data between 1949 and 2003 both for men and women. Another case is also considered based on a restricted data set corresponding to the period 1989–2003. The model fitted to the data of the period 1949–2003 forecasts increasing mortality rates for men between ages 45 and 55, pointing out that the Lee-Carter method is hardly applicable for countries where mortality rates exhibit trends as peculiar as in Hungary. However, models fitted to the data for the last 15 years both for men and women forecast decreasing trends similarly to the case of countries where the method was successfully applied. Hence one gets a better fit in this way, however, further concerns suggest that the Lee-Carter model, which is celebrated and widely used in actuarial practice, does not necessarily give sufficiently good prediction.

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Abstract  

Starting from the principles of sol-gel method, developed originally for the preparation of nuclear fuels in spherical form, their application to the preparation of microspheres of various non-nuclear elements is presented. In addition to the preparative conditions of the primarily hydroxidic spheres, their conversion into other insoluble compounds such as phosphates, ferrocyanides, sulphides, etc. is described. These sol-gel products work very well as ion-exchangers; their sorption properties are quite comparable to those of the common powder sorbents, the sphere from being their main beauty. Applicability of these sorbents as well as their limitations are also discussed.

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