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Start Over Coverage 185-194

2. Evaluation of cold stress of young industrial chicory (Cichorium intybus L.) by chlorophyll a fluorescence imaging. II.. Dark relaxation kinetics

Creator:
Lootens, P., Devacht, S., Baert, J., Van Waes, J., Van Bockstaele, E., and Roldán-Ruiz, I.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
botanika, botany, chilling, energy-dependent quenching, nonphotochemical quenching, photoinhibition, and state-transition-dependent quenching
Language:
Multiple languages
Description:
Industrial chicory, Cichorium intybus L., has rather poor early vigour under the typical early spring morning conditions of low temperatures and high light intensity. Screening tools are being developed to assess the cold tolerance/sensitivity of young industrial chicory plants under these conditions. Refinement of such tools requires better understanding of the plants' physiological responses. In this paper we discuss the effects of growth temperature (GT), measurement temperature (MT), and measuring light intensity (ML) on the relaxation of the Kautsky curve. We chose the chicory variety 'Hera', as it is known to possess a good average early vigour. Young plants of the variety 'Hera' were grown at three temperatures (GT): 16°C (reference), 8°C (intermediate), and 4°C (cold stress). The dark relaxation kinetics were analyzed at different light intensities (ML) in combination with different measurement temperatures (MT). The three components of the nonphotochemical quenching process (NPQE, NPQT, and NPQI) were determined. NPQE was not affected by GT but was significantly affected by MT and ML. NPQT and NPQI were affected by all factors and their interactions. An acclimation effect for plants grown at low GT was detected. Acclimation resulted in lower NPQT and NPQI values. The halftime of the inhibition depending on NPQ (NPQI) was not affected by any of the factors investigated. Based on the data generated, we conclude that NPQI is a valuable parameter for screening the cold sensitivity of young industrial chicory plants. and P. Lootens ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Physical structure and diagnostics of solar active regions deduced from optical, visible and UV observations

Creator:
Lemaire, P.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
solar active regions, solar surface, and diagnostics
Language:
Czech
Description:
Since the 1978-79 Skylab Workshop on Solar Active Regions, significant progress has been made in the diagnostic and modeling of active solar structures. This paper review the status of our knowledge of the physical properties of active regions in the photosphere, chromosphere and transition zone, as inferred from observations. Plages are the main active region which we study. A comparison with quiet Sun and some other solar structures is made in order to in order to emphasize the spedificity of plages properties. To conclude we present some requirements for new observations and theoretical developments to improve our understanding of the physical structure of solar active regions.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

4. Probing reaction centre protonation by electrochromic absorption changes of cofactors in Rhodobacter sphaeroides

Creator:
Kálmán, L., Turzó, K., and Maróti, P.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Electrochromic changes of the Qy absorption bands of chromophores (dimeric and monomeric bacteriochlorophylls and bacteriopheophytins) were measured in reaction centres from purple photosynthetic bacteria Rhodobacter sphaeroides. The observed electrochromic effects could be decomposed to changes dne to negative charge on the acceptor quinone complex and positive charge on the dimer. The coiďumed additivity (superposition) of the electrochromic effects indicated that the chromophores had fixed geometry in redox transitions. The Qy absorption band of the bacteriopheophytin proved to be a very sensitive indicator of the relaxational processes of electric charges (protons and/or cations) in the vicinity of the quinones: (7) the bandwidth was affected by pH around 10 which was close to the pK of protonation of the reduced primary quinone, (2) absorption changes at 748 nm were observed after flash excitation with time constant characteristic to that of light- induced proton binding in reaction centres.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

5. Realization theory methods for the stability investigation of nonlinear infinite-dimensional input-output systems

Creator:
Reitmann, Volker
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
infinite dimensional Volterra integral equation, realization theory, absolute instability, and frequency-domain method
Language:
English
Description:
Realization theory for linear input-output operators and frequency-domain methods for the solvability of Riccati operator equations are used for the stability and instability investigation of a class of nonlinear Volterra integral equations in a Hilbert space. The key idea is to consider, similar to the Volterra equation, a time-invariant control system generated by an abstract ODE in a weighted Sobolev space, which has the same stability properties as the Volterra equation.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

6. Spectroscopic characterization of protochlorophyllide photoreduction in the greening leaf

Creator:
Franck, F., Barthelemy, X., and Srtrzalka, K.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Room temperature absorbance and 77 K fluorescence measurements were ušed in order to identity Pchlide and Chlide spectral forms involved in protochlorophyllide photoreductíon in greening leaves of barley. Pchlide55o (the subscript refers to the in vivo absorbance maximum of the pigment) is the main photoactíve Pchlide throughout the first 8 h of greening. Its photoreductíon triggers a succession of Chl(ide) spectral forms that are identícal to those normally found after photoreductíon in uitírradiated leaves. Afler an actinic radiation pulse, Chlide5g4 appears within 2 s from an intermediate at shorter wavelength and is transformed to Chlide572 in less than 2 min. The time-scale of the shifts is remarkably shorter than in unirradiated leaves, which is consistent with the acceleratíon of Chl accumulatíon during greening. Pchlide63o and Pchlide64o act as precursors of Pchlide65o during its regeneration, which exhibits a marked inhibition at temperatures above 30 °C.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public