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1

Seasonal changes in phytoplankton and bioindices in the southern part of Lake Jeziorak (NE Poland)

Dembowska E. A., Józefowicz S.

Oceanological and Hydrobiological Studies

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2015

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Vol. 44, No. 1

1--10

EN

The structure of phytoplankton communities of Lake Jeziorak was presented for the first time. The objective of our research was qualitative and quantitative analysis and bioindices of phytoplankton during and outside the tourist season. Analysis of phytoplankton assemblages were performed in 2011-2012. A total of 96 taxa were identified in Lake Jeziorak, mainly: Cyanobacteria - 20, Bacillariophyceae - 49, and Chlorophyta − 19. Biomass of the phytoplankton varied from 10 mg l−1 in October to 29 mg l−1 in May. In the whole research period, Cyanobacteria dominated and represented up to 68% of the total biomass. The cyanobacterial blooms were constantly observed. Biomass in the summer period was composed of filamentous Aphanizomenon gracile, Limnothrix redekei, Planktothrix agardhii and Pseudanabaena limnetica. Outside the holiday season, i.e. in autumn and spring, filamentous Cyanobacteria accompanied cryptomonads in phytoplankton. The species composition, the biomass of phytoplankton, and TSI indicate the hypertrophic conditions of the lake. Phytoplankton in Lake Jeziorak was in a state of equilibrium for almost the entire study period. S1 was a dominant group and its abundance and biomass did not change by more than 10%. There was no significant direct effect of the seasonal tourism impact on the development of phytoplankton in Lake Jeziorak

2

Discrete modeling of the three species syn-ecosystem with unlimited resources

Prasad B. H.

Journal of Applied Mathematics and Computational Mechanics

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2015

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Vol. 14, nr 2

85--93

EN

In this paper, the three species syn-ecosystem is comprised of a commensal (S1), two hosts S2 and S3, i.e. S2 and S3 both benefit S1 without getting themselves affected either positively or adversely. Further, S2 is a commensal of S3, S3 is a host of both S1, S2 and all the three species have unlimited resources. The basic equations for this model constitute as three first order non-linear coupled ordinary difference equations. All possible equilibrium states are identified based on the model equations at two stages and criteria for their stability are discussed. Further, the numerical solutions are computed for specific values of the various parameters and the initial conditions.

3

Effective energy integral functionals for thin films in the Orlicz-Sobolev space setting

Laskowski W., Nguyen H. T.

Demonstratio Mathematica

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2013

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Vol. 46, nr 3

585--604

EN

We consider an elastic thin film as a bounded open subset ω of R2. First, the effective energy functional for the thin film ω is obtained, by Γ-convergence and 3D-2D dimension reduction techniques applied to the sequence of re-scaled total energy integral functionals of the elastic cylinders (…) as the thickness ε goes to 0. Then we prove the existence of minimizers of the film energy functional. These results are proved in the case when the energy density function for the elastic cylinders has the growth prescribed by an Orlicz convex function M. Here M is assumed to be non-power-growth-type and to satisfy the conditions (…) and (…) (that is equivalent to the reflexivity of Orlicz and Orlicz–Sobolev spaces generated by M). These results extend results of H. Le Dret and A. Raoult for the case M(t) = (…) for some (…).

4

Stability analysis and comparison of the models for carcinogenesis mutations in the case of two stages of mutations

Foryś U.

Journal of Applied Analysis

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2005

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Vol. 11, nr 2

283-302

EN

The present paper is focused on the analysis of three very simple models of carcinogenesis mutations that are based on reaction-diffusion systems and Lotka-Volterra food chains. We consider the case with two stages of mutations and study the systems of three reaction-diffusion equations with zero-flux boundary conditions. We focus on the Turing instability and show that this type of instability is not possible for these models. We also propose some modifications of the considered equations. Results are illustrated by computer simulations.

5

When Do Equilibria of Positive 2D Roessner Model Are Strictly Positive

Kaczorek T.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2002

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Vol. 50, Nr 3

221--227

EN

Equilibrium states of the positive 2D Roessner model with constant strictly positive inputs are defind. It is shown that the equilibrium states of an asymptotically stable 2D Roessner model are unique and positive and they are strictly positive if and only if the matrix A of the model is irreductible.

6

Estimating macropore water content in model water-clay system

Olchawa A.

Archives of Hydro-Engineering and Environmental Mechanics

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1999

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Vol. 46, nr 1-4

119-126

EN

The paper presents the method tor the estimation of macropore water content in model clays. The method is based upon the equilibrium state of the clay-water system external load at the end of the swelling process. The results of estimations by this method conformed very well with earlier results obtained from another methods.