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Problematyka poufności, autentyczności, integralności oraz niezaprzeczalności danych w systemach wieloagentowych1

Strzałek M., Pałka P.

Studia Informatica

2012

Vol. 33, nr 2B

217-227

W pracy rozważana jest problematyka bezpieczeństwa komunikacji w systemach wieloagentowych. Dodatek do systemu JADE, o nazwie JADE-S, dostarcza odpowiednich narzędzi do zapewnienia bezpieczeństwa w systemie wieloagentowym. Jest on rekomendowany do realizacji bezpieczeństwa w systemach wieloagentowych opartych na JADE. W pracy opisano, w jaki sposób mogą być zapewnione odpowiednie poziomy poufności, niezaprzeczalności oraz autentyczności wysyłanych komunikatów. Ponadto, rozważa się możliwość negocjacji poziomu zabezpieczeń oraz odpowiedniego algorytmu szyfrowania.

The paper considers the issue of security of communication in multi-agent systems. JADE-S framework provides the appropriate tools to ensure security in a multi-agent system. It is recommended to implement security in multi-agent systems based on JADE. Aim of this study is to describe how appropriate levels of confidentiality, non-repudiation and data authentication can be provided. Moreover, we consider the possibility of negotiating an appropriate level of security and encryption algorithm.

Growth rate of duckweeds (Lemnaceae) in relation to the internal and ambient nutrient concentrations - testing the Droop and Monod models

Kufel L., Strzałek M., Wysokińska U., Biardzka E., Oknińska S., Ryś K.

Polish Journal of Ecology

2012

Vol. 60, nr 2

241-249

The Monod model describes the relationship between growth rate and ambient nutrient concentration, the Droop model focuses on internal nutrient resources as the driving factor. Both were applied mainly to explain phytoplankton dynamics in lakes or in experimental cultures. Our test plants were two species of duckweeds - Lemna minor L. and Spirodela polyrhiza (L.) Schleiden sampled from 18 natural stands situated in 6 different water bodies. Plants were grown outdoor in original lake water or in mineral media of varying N and P concentrations (0-21 mg N-NO3 L[^-1] and 0-1853 [mu]g P-PO4 L[^-1] for L.minor and 0-4.2 mg N-NO3 L[^-1] and 0-371 [mu]g P-PO4 L[^-1] for S. polyrhiza). Moreover, we analysed concentrations of mineral forms of N and P in lake water and tissue nutrient concentrations in plants. Tissue N of both plants was significantly correlated with ambient inorganic nitrogen sources, no such relationship was observed for tissue P. The growth rate of both plants measured under experimental outdoor conditions was better explained by tissue N and P variability (the Droop model) than by the external nutrient availability (the Monod model). The latter also failed to fit the growth rate of both plants in artificial mineral media with a decreasing gradient of N and P concentrations. The plants grew at the expense of internal N and P resources which remarkably declined during 9-day long experiments. Calculated minimum tissue contents (11.19 [plus or minus] 1.11 mg N g[^-1] and 0.97 [plus or minus] 0.07 mg P g[^-1] in L. minor and 6.10 [plus or minus] 1.85 mg N and 1.25 [plus or minus] 0.37 mg P g[^-1] in S. polyrhiza) show that the latter species would be a superior competitor under N limiting conditions and the former - under P limitation. We confront obtained results with literature data on N uptake kinetics and postulate that the luxury consumption of nutrients and plant growth dependent mainly on internal N and P resources might be an adaptation of duckweeds to varying habitat conditions typical of astatic water bodies.