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  • Author or Editor: L. Papp x
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It is an essential property of diversity indices that increases in the abundance or frequency of the most frequent species result in a decline in diversity, whereas increases in the abundance of the rarest species lead to an increase in diversity. At the same time, without resort to mathematical operations, it is difficult to determine the sign and measure of alteration in diversity when increasing an additional frequency while leaving all others unaltered. A more concrete task is to determine the index response to a partial alteration of fixed percentage in the frequencies of the multi-species community or collection. Plotting the observed responses or sensitivity values against the frequencies concerned makes possible a good overview of the sensitivity relations. The mathematical groundwork of sensitivity analysis with respect to diversity indices has already been elaborated. To date, however, the methodological possibilities engendered by such analyses have yet to be exploited. In the present work, sensitivity relations are discussed for apple-bait Drosophilidae collections and human faeces trap collections of flies inhabiting brook valleys in the low mountains of Hungary. Inspection of the results enables us to identify the range of frequencies at which significant increases or decreases in diversity will result. A relatively small increase of so-called nearly indifferent or quasineutral frequencies lying within that frequency range has a trivial influence on diversity values. While sensitivity is astonishingly sizeable with a few dominant case numbers, all other frequencies scarcely influence the index value.

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Adult fly collections were made in May and August 2006, from the mud of a salty lake in the Kiskunság National Park, Hungary. We collected 21,600 individuals of 62 species in May and 18,400 individuals of 81 species in August, giving a total of 103 species (only 40 appearing in both seasons). Dominant species were different in the two collections. Five species are new for the Hungarian fauna. Diversity measured by several indices was higher in the May collection. We observed simultaneously a nearly lognormal distribution and a power-law like behaviour of the abundances.

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Abstract  

A CAMAC system was installed for pulse height analysis and correction of counting losses due to the dead-time of a multichannel analyzer and the pulse pile-up. A computer program was developed to control the whole system, and to collect and store data in both conventional and cyclic measurement modes.

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Abstract  

The problem of converting measured intensities into mass concentrations arises from the fact that the measured intensity of a characteristic X-ray line of an element or compound depends not only on the mass concentration of that element or compound but also on the nature and abundance of the other constituents of the specimen. In this work the empirical coefficient method which comprises both absorption and enhancement effects of each element on each other element by parameters independent of mass concentrations was used for correction of enhancement effects from antimony and praseodymium on bromine in two groups of samples. The results of analysis of bromine shows a relative error of not more than ±4%.

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Abstract  

A method is described for the simultaneous determination of cadmium, antimony and praseodymium by 14-MeV neutron activation analysis based on characteristic X-ray spectrometry. The results of analysis show a relative error not higher than ±5%, when diluted with H3BO3 /90%/ and utilizing the internal standard method to minimize the interelement effects.

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Abstract  

14 MeV neutron activation followed by X-ray spectrometry was applied to the simultaneous nondestructive determination of cadmium, antimony and bromine, utilizing praseodymium as an internal standard. The results of analysis show a relative error not higher than ±5%, when the samples were diluted with H3BO3 -5% to minimize the interelement effects.

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Abstract  

The empirical coefficient method represents the absorption and enhancement effect of each element on each other by parameters independent of mass concentrations. This method is used together with the internal standard method for the determination of cadmium, bromine and selenium by 14 MeV neutron activation followed by X-ray spectrometry. The results of analysis show a relative error not more than ±5%.

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Abstract  

The fundamental parameters method (FPM) for X-ray fluorescence (XRF) has been applied to determine the MN, Cr and Sr components of aluminium wires and sheets. The results are compared with neutron activation analysis (NAA) and atomic absorption spectrometry (AAS). The FPM does not require standards, however, it requires the spectra of the pure element for the concentration determination.

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Abstract  

An activation analytical method has been developed for determining Cd, Ag, Sb, Se, Br by 14 MeV neutron-induced X-ray emission spectroscopy using Pr as an internal standard. A good correlation was obtained between the activity ratio, RA o and the weight ratio, RW. Results are given after correction for self-absorption and without correction. The results are comparable in both cases when dilution with H3BO3 (90%) is applied. The elements listed can be determined at minor concentrations (0.01%) with a relative error not more than ±5%.

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Abstract  

The intensity of characteristic X-rays emitted from one element may be reduced by partial absorption by other elements in the matrix, or alternatively it is enhanced by their presence. In this work the enhancement effect of antimony on bromine, cadmium and selenium are given. The dependence of the specific activity of each element /Cd, Br and Se/ on the ratio of the weight of Sb to that of the element is given, when the concentration of Sb is not very low /-5%/.

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