Chlorophyll (Chl) fluorescence technique was ušed to monitor Cu damage in photosynthetic process in intact leaves of a Cu-tolerant {Silene conipacla) and a non- Cu-tolerant {Thlaspi ochroleucum) species. The initial fluorescence level (Fq) increased whereas the variable fluorescence (Fy) decreased in T. ochroleucum under low and high Cu-dose, suggesting injuries both in reaction centie level and in photooxidizing side of photosystem 2 (PS2). The photochemistiy activity of PS2, Fy/Fp, revealed a slight increase under 8 pM Cu in both species, while at 160 pM of Cu a strong inhibition in T. ochroleucum was observed. The Fp/F() ratio appeared to increase under low Cu dose, however the high Cu dose in nutrient solution resulted in damage to the thylakoid structure affecting the PS2 donor and acceptor side, mainly in T. ochroleucum. The slow part of the Chl fluorescence induction cuiwe was affected more by Cu stress, than the fast one. At low Cu concentration the Rfd value increased in S. compacla but decreased in T. ochroleucum. Fligh Cu dose induced an almost complete inhibition of this parameter, that was more severe in the non-tolerant plants. Yet, low Cu dose enhanced the Chl content in S. compacla but on exposure to 160 pM Cu the symptoms of chlorosis were more visible in T. ochroleucum. Thus, excess of Cu has direct negative effects on the photosynthetic electron transport that may be accounted for by the destruction of the photosynthetic pigments.
Single element optical systems are nowadays used very seldom due their limited optical properties. Possible solution can be the use of the variable optical components. Without need of movable mechanical parts and currently keeping small dimensions it’s possible to get optical systems with variable focal length in wide range with just one optical element. In this article there are described at this time the most often used designs of these lenses. Furthermore there is also a theoretical optical analysis for selected focal lengths of Varioptic Arctic 314 and Varioptic 416 liquid lenses included. and Jednoprvkové optické systémy jsou v současné době používány velice zřídka, a to z důvodu jejich omezených optických vlastností. Jedno z možných řešení tohoto problému může být použití optických prvků s proměnnými optickými vlastnostmi. Tyto nám umožní konstrukci optických systémů s proměnnou ohniskovou vzdáleností v širokém rozsahu bez potřeby užití pohyblivých prvků a při zachování kompaktních rozměrů. V článku jsou popsány v současné době nejvíce používaná konstrukční řešení těchto čoček. Dále je také provedena analýza vybraných optických vlastností kapalinových čoček Varioptic Arctic 314 a Varioptic Arctic 416 pro některé hodnoty z výrobcem udávaného rozsahu ohniskových vzdáleností.
We study the semilinear problem with the boundary reaction −∆u + u = 0 in Ω, ∂u ∂ν = λf(u) on ∂Ω, where Ω ⊂ R N , N > 2, is a smooth bounded domain, f : [0, ∞) → (0, ∞) is a smooth, strictly positive, convex, increasing function which is superlinear at ∞, and λ > 0 is a parameter. It is known that there exists an extremal parameter λ ∗ > 0 such that a classical minimal solution exists for λ < λ∗ , and there is no solution for λ > λ∗ . Moreover, there is a unique weak solution u ∗ corresponding to the parameter λ = λ ∗ . In this paper, we continue to study the spectral properties of u ∗ and show a phenomenon of continuum spectrum for the corresponding linearized eigenvalue problem.
A complete survey is presented of photosynthetic patfaway in the 27 species of the genus Cyperus occurring in Europe. Among them, tíiere are 20 species vsdth C4 photosynthesis and 7 species with C3 photosynthesis. In 14 species the pathway is repoited for the first time. Wifli different pattems, both C3 and C4 types occur from the Mediterranean region (35 °N) to the cool temperate region (52 “N). Atlantic current may háve a striking effect on the distňbution of wetland C4 sedges. Although the existence of rhizomes in C4 Cyperus perennials favours their survival at short summers of centra! and west Europe, low temperature at latě summer in the regions prevents them to complete seed development. Leaf anatomy indicates that diy summer in Mediterranean regions limits some of them due to dieir lavish water requirement. In the eastem and north Europe a long period of low temperature in winter may be the most important reason for the absence of C4 Cyperus species.