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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
- Rojdestvenski, I, et al.
(författare)
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A two-dimensional many-body system with competing interactions as a model for segregation of photosystems in thylakoids of green plants
- 2000
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Ingår i: European Biophysics Journal. - 0175-7571 .- 1432-1017. ; 29:3, s. 214-220
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Tidskriftsartikel (refereegranskat)abstract
- We address the segregation of photosystems I (PSI) and II (PSII) in thylakoid membranes by means of a molecular dynamics method. We assume a two-dimensional (in-plane) problem with PSI and PSII being represented by particles with different values of negative charge. The pair interactions between particles include a screened Coulomb repulsive part and am exponentially decaying attractive part. Our modeling results suggest that the system may have a complicated phase behavior, including a quasi-crystalline phase at low ionic screenmg, a disordered phase and: in addition, a possible "clotting" agglomerate phase at high screening where the photosystems tend to clot together. The relevance of the observed phenomena to the stacking of thylakoid membranes is discussed.
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| 4. |
- Rojdestvenski, I, et al.
(författare)
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Segregation of photosystems in thylakoid membranes as a critical phenomenon
- 2002
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Ingår i: Biophysical Journal. - 0006-3495 .- 1542-0086. ; 82:4, s. 1719-1730
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of the two photosystems, PSI and PSII, in grana and stroma lamellae of the chloroplast membranes is not uniform. PSII are mainly concentrated in grana and PSI in stroma thylakoids. The dynamics and factors controlling the spatial segregation of PSI and PSII are generally not well understood, and here we address the segregation of photosystems in thylakoid membranes by means of a molecular dynamics method. The lateral segregation of photosystems was studied assuming a model comprising a two-dimensional (in-plane), two-component, many-body system with periodic boundary conditions and competing interactions between the photosystems in the thylakoid membrane. PSI and PSII are represented by particles with different values of negative charge. The pair interactions between particles include a screened Coulomb repulsive part and an exponentially decaying attractive part. The modeling results suggest a complicated phase behavior of the system, including quasi-crystalline phase of randomly distributed complexes of PSII and PSI at low ionic screening, well defined clustered state of segregated complexes at high screening, and in addition, an intermediate agglomerate phase where the photosystems tend to aggregate together without segregation. The calculations demonstrated that the ordering of photosystems within the membrane was the result of interplay between electrostatic and lipid-mediated interactions. At some values of the model parameters the segregation can be represented visually as well as by analyzing the correlation functions of the configuration.
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| 5. |
- Rojdestvenski, I, et al.
(författare)
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Thermodynamics of complexity
- 2003
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Ingår i: Physica A. - 0378-4371 .- 1873-2119. ; 320, s. 318-328
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Tidskriftsartikel (refereegranskat)abstract
- The definition of complexity, simultaneously introduced by Kolmogorov and Chaitin, has given a numerical measure to what was previously defined only at an intuitive level. This measure, useful as it is, becomes hard to utilise when one deals with the complexity of most real systems, and biological objects in particular. We try to overcome this difficulty by discussing a possible thermodynamic definition of complexity based on energy balance. The Kolmogorov-Chaitin definition of complexity thus relates to our thermodynamic definition in a similar way as the probabilistic definition of entropy relates to the thermodynamic one. In the framework of this intuitive treatment it is discussed how the complexity of a biological system may depend on the variability of the environmental conditions. A specific illustration of this approach is given using some numerical modeling examples. (C) 2002 Elsevier Science B.V. All rights reserved.
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