Wyniki wyszukiwania - BazTech

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Diatom assemblages as indicators of salinity gradients : a case study from a coastal lake

Rzodkiewicz M., Gąbka M., Szpikowska G., Woszczyk M.

Oceanological and Hydrobiological Studies

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2017

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Vol. 46, No. 3

325--339

EN

In order to understand the variability of diatoms in coastal lakes and its relationship to salinity, the authors have conducted a two-year study at Lake Resko Przymorskie (the Southern Baltic coast), which has a salinity between 1.9-4.8 PSU. Redundancy analysis (RDA) was used to describe the relationship between the species composition and selected variables. Four of the 10 measured variables of surface water chemistry (Cl- and PO43- concentrations, temperature, and pH) significantly explained 23% of the variation in the diatom species composition. We found 82 taxa of diatoms (mostly tychoplanktonic) and determined the optimum and tolerance levels of salinity for predominant taxa (49 species with minimum 2% abundance). The optimum chloride concentration for the predominant diatoms ranged from 1471 to 2961 mg Cl- l-1. The most abundant brackish water species was Pseudostaurosiropsis geocollegarum. Brackish-freshwater diatoms were represented by Cyclotella atomus, Cyclotella meneghiniana, Diatoma tenuis and Staurosira subsalina. The most abundant fresh-brackish water diatoms were Amphora pediculus, Fragilaria sopotensis, Hippodonta hungarica, Pseudostaurosira brevistriata and Staurosira construens. Freshwater taxa accounted for as little as 1% of the population. This study provides new data on the ecology of coastal lakes and the possibility of using diatom-based transfer functions in the reconstruction of past environmental changes.

2

Employing linear artificial neural networks in property appraisal and valuation – possible applications

Górak M.

Geomatics, Landmanagement and Landscape

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2017

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no. 1

17--24

EN

Transactional price is the result of some kind of free market game, and of independent decisions taken by the parties to the transaction. Prices depend on a number of factors, specific to the local real estate market. The impact of some factors is fixed, while others are dependent on the location of the property. Therefore, research into the determination of rules that would describe the relationship between the market price of the real estate, and its market characteristics, remain valid. The article presents the possibilities of applying linear artificial neural networks to real estate valuation. Using a database, the artificial linear neural network is developing a regression model, which produces the results that oscillate close to the market value of the property. The necessary condition is the creation of a database that is representative of the given real estate market.

PL

Cena transakcyjna to wynik pewnego rodzaju gry rynkowej oraz suwerennych decyzji podejmowanych przez strony transakcji. Ceny uzależnione są od szeregu czynników charakterystycznych dla danego lokalnego rynku nieruchomości. Wpływ pewnych czynników jest niezmienny, inne zaś zależne są od lokalizacji nieruchomości. Dlatego badania nad określeniem reguł opisujących zależność pomiędzy ceną rynkową nieruchomości a jej cechami rynkowymi są wciąż aktualne. Artykuł przedstawia możliwości aplikacyjne sztucznych liniowych sieci neuronowych w wycenie nieruchomości. Sztuczna liniowa sieć neuronowa na podstawie bazy danych, opracowuje model regresyjny uzyskujący wyniki oscylujące w pobliżu rynkowej wartości nieruchomości. Warunkiem koniecznym jest utworzenie bazy danych, reprezentatywnej dla danego rynku nieruchomości.

3

Distribution of Cladocera communities across a climate gradient in shallow lakes from Croatia to Hungary: a preliminary study

Kӧvér C, Korponai J, Katalinic A, Bereczki C

Studia Quaternaria

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2012

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Vol. 29

45--52

EN

Cladocera communities in surface sediments of seven lakes were sampled from the Mediterranean to north Hungary. Conductivity, pH, primary ions (Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, CO32-) and macrophyte coverage were measured as contributed environmental parameters for the distribution of cladoceran communities across the lakes. Thirtytwo cladoceran species were found in the seven lakes. The recorded species have wide tolerance spectra, and are able to colonize very different kind of habitats. The most common and abundant species were Chydorus sphaericus, Alona rectangula and Bosmina longirostris. Lake area, latitude, macrophyte coverage, pH, conductivity and hardness were found to be the most determinant environmental variables in the distribution of cladoceran species. This study revealed that although the lakes show a clear separation in environmental parameters the composition and distribution of Cladoceran communities differ only slightly across the investigated geographical gradient.