Evolution of plant reproduction: from fusion and dispersal to interaction and communication

Based on the existing data concerning the evolution of the sexual reproduction, it is argued that the processes of sex differentiation and interactions play a key role in evolution. From the beginning environment and organism are unified. In a changing dynamic environment life originates and the interaction between life and environment develops from simple to more complex organisms. Sexual reproduction is introduced after the origin of meiosis and is a key process in evolution. The asexual reproduction process prepares to dispersal. Sexual reproduction process adds the genome renewal and the gamete-gamete interaction. Reproduction and dispersal are connected and the process of reproduction has similarities between asexual and sexual reproduction. Unicellular algae develop the physiological and morphological sex differentiation. Sex differentiation is connected with the way of dispersal. The step to multicellular plants introduces cell isolation after meiosis and by the stay on the mother plant within a cell or organ, plant-cell apoplastic interaction originates and by prolonged stay the plant-plant interaction. This stay influences the type of dispersal. A life cycle with alternation of generations and two moments of dispersal permits plants to go on land. In ferns a shift in the moment of sex differentiation to meiospore happens and the stay of the macrospore leads to the seed plants. In water all types of sexual reproduction, interactions and the alternation of generations are prepared and these are used to conquest land. On land the biotic dispersal is realized. The phylogeny of sexual reproduction reveals that the sex differentiation and interaction are the main causes in the evolution of sexual reproduction. Sexual reproduction shows interactions during gamete fusion, between organism and environment and in multicellular plants between organisms. With respect to other types of interaction as in symbiosis or the nutrient chain, interaction is considered as an important action which is based on a persisting cooperation and points to a push during evolution. The push is expressed as communication: the driving force in the evolution. Based on the interactions between organisms and interactions between organisms and the dynamic environment, communication is considered as a driving force leading to the evolution as explained in the development of plant reproduction. Consequences for reproduction, its regulation and the process of evolution are discusse

How does turnover affect turnout? Government alternation and voter participation in parliamentary democracies

A crucial difference between political systems is the nature of government alternation: that is, whether when a government changes, all parties now in government were previously in opposition ('wholesale alternation') or whether just some parties were ('partial alternation') (Mair 1997). Bergman and Strom (2011) suggest that wholesale alternation gives voters a clear choice between alternative governments and allows them to hold the government accountable, while partial alternation is associated with one (centre) party becoming a (near-) permanent government party who can govern with either the parties to its right or to its left. However, this relationship has not been tested. We propose to examine the effect of partial and wholesale alternation on turnout in a large-N cross-country study, showing that there is an interaction effect between disproportionality and wholesale turn-out. Wholesale decreases turn-out but only when it when disproportionality is high.</p

The ground state properties of the spin-1/2 transverse Ising chain with periodically varying bonds and fields

Using continued fractions we study the ground state properties of the spin-1/2 Ising chain in a transverse field with periodically varying interaction strengths and external fields. We consider in detail the chain having the period of modulation of interactions equals 2 and compare the results obtained with those corresponding to the spin-1/2 isotropic XY chain in a transverse field. In contrast to the behaviour of the transverse XY chain, the transverse Ising chain does not exhibit a step-like magnetization vs. field dependence caused by the alternation of bonds, its susceptibility exhibits a logarithmic singularity at the field determined by interaction strengths, and it is stable with respect to spin-Peierls dimerization.Comment: 11 pages, latex, 4 figure

Structural Instability in Polyacene : A Projector Quantum Monte Carlo Study

We have studied polyacene within the Hubbard model to explore the effect of electron correlations on the Peierls' instability in a system marginally away from one-dimension. We employ the projector quantum Monte Carlo method to obtain ground state estimates of the energy and various correlation functions. We find strong similarities between polyacene and polyacetylene which can be rationalized from the real-space valence-bond arguments of Mazumdar and Dixit. Electron correlations tend to enhance the Peierls' instability in polyacene. This enhancement appears to attain a maximum at $U/t \sim 3.0$ and the maximum shifts to larger values when the alternation parameter is increased. The system shows no tendency to destroy the imposed bond-alternation pattern, as evidenced by the bond-bond correlations. The cis- distortion is seen to be favoured over the trans- distortion. The spin-spin correlations show that undistorted polyacene is susceptible to a SDW distortion for large interaction strength. The charge-charge correlations indicate the absence of a CDW distortion for the parameters studied.Comment: 13 pages, 10 figures available on reques

Gestire l'alternanza L1/L2 nella classe di lingua. Per una riflessione sull'insegnamento delle lingue straniere nella scuola in Italia

This paper examines the phenomenon of alternation between L1 and L2 in classroom interaction in the context of language teaching and learning. The focus is on a specific teaching context, namely the foreign language class where there is a shared L1 between students and learners, and on the teacher's linguistic choice in classroom interaction. The paper is based on an empirical research, carried out in some Italian secondary schools, by administering a questionnaire addressed to teachers and collecting a corpus of classroom interactions. After a review of the main studies dealing with language alternation in the context of language teaching, we consider some recommendations suggested in the field of the educational policy in Europe and especially in Italy, in order to assess whether and to what extent the problem of managing language alternation in the language class is dealt with in institutional programmatic documents. Then we present the results of the empirical research. The aim of this paper is principally descriptive and is related to the identification of pragmatic rules for the management of language alternation in a foreign language class. However, the analysis also tries to evaluate the different ways of managing the L1/L2 alternation from the point of view of language teaching, in order to plan teacher training and make some methodological suggestions for the teaching practice

Homothetic Wyman Spacetimes

The time-dependent, spherically symmetric, Wyman sector of the Unified Field Theory is shown to be equivalent to a self-gravitating scalar field with a positive-definite, repulsive self-interaction potential. A homothetic symmetry is imposed on the fundamental tensor, and the resulting autonomous system is numerically integrated. Near the critical point (between the collapsing and non-collapsing spacetimes) the system displays an approximately periodic alternation between collapsing and dispersive epochs.Comment: 15 pages with 6 figures; requires amsart, amssymb, amsmath, graphicx; formatted for publication in Int. J. Mod. Phys.

Variational states for the spin-Peierls system

We introduce a family of Jastrow pair product states for quasi one-dimensional spin systems. Depending on a parameter they interpolate between the resonating valence bond ground state of the Haldane-Shastry model describing a spin liquid and the (dimerized) valence bond solid ground states of the Majumdar-Ghosh spin chain. These states are found to form an excellent basis for variational studies of Heisenberg chains with next nearest neighbour interaction and bond alternation as realized in the spin-Peierls system CuGeO_3.Comment: RevTeX+epsf macros, 24 pp. incl. figures, some references adde

The Patterning of Language Alternation in a Greek Supplementary School

This paper reports on the findings of a research project that explored language alternation patterns in a Greek supplementary school. Classroom interactions between bilingual in Greek and English pupils and the teacher were transcribed and then analysed based on Auer (1984, 2000) and Gafaranga’s (1999, 2000, 2007) conversation analytic model. The key findings revealed that different organisational patterns of language alternation correspond to different functions. When the main purpose of interaction was language practice, the interlocutors adopted the Greek monolingual medium, whereas when language alternation was used for the establishment of interpersonal relations, the speakers adopted the bilingual medium