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2. On reflexivity and hyperreflexivity of some spaces of intertwining operators

Creator:
Zajac, Michal
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
intertwining operator, reflexivity, C0 contraction, weak contraction, and hyperreflexivity
Language:
English
Description:
Let T, T′ be weak contractions (in the sense of Sz.-Nagy and Foia¸s), m, m′ the minimal functions of their C0 parts and let d be the greatest common inner divisor of m, m′ . It is proved that the space I(T, T′ ) of all operators intertwining T, T′ is reflexive if and only if the model operator S(d) is reflexive. Here S(d) means the compression of the unilateral shift onto the space H 2 ⊖dH2 . In particular, in finite-dimensional spaces the space I(T, T′ ) is reflexive if and only if all roots of the greatest common divisor of minimal polynomials of T, T′ are simple. The paper is concluded by an example showing that quasisimilarity does not preserve hyperreflexivity of I(T, T′ ).
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4. Simulation of Pulse-Amplitude-Modulated (PAM) fluorescence: Limitations of some PAM-parameters in studying environmental stress effects

Creator:
Juneau, P., Green, B. R., and Harrison, P. J.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
copper, Chlamydomonas, non-quenched fluorescence, parameter calculation, and photochemical quenching
Language:
Multiple languages
Description:
Fluorescence parameters obtained during steady-state electron transport are frequently used to evaluate photosynthetic efficiency of plants. We studied the behaviour of those parameters as a function of irradiance-adapted fluorescence yields FS and F'M. Applied simulations showed that photochemical quenching evaluated by qP is greatly influenced by the steady-state fluorescence level (FS), and that its evolution is not complementary to non-photochemical quenching (qN). On the other hand, the relative photochemical and non-photochemical quenching coefficients (qP(rel) and qN(rel)) proposed by Buschmann (1995) represent better the balance between the energy dissipation pathways. However, these relative parameters are also non-linearly related when the FS level is varied. We investigated the application of a new parameter, the relative unquenched fluorescence (UQF(rel)) which takes into account the fraction of non-quenched fluorescence yield (FS), which is related to closed photosystem 2 reaction centres not participating in electron transport. By using computer simulations and real in vivo measurements, we found that this new parameter is complementary to qP(rel) and qN(rel), which may facilitate the use of PAM fluorescence as diagnostic tool in environmental studies. and P. Juneau, B. R. Green, P. J. Harrison.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public