2 resultados para Formal aspects

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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Semi-presidential systems of democratic governance risk ending up in a stalemate when it is not clear which of the two „heads” – head of State or head of Government – shall take the lead. The current political situation in Romania features some of the commonly observed characteristics of such an institutional blockade. However, after addressing these formal aspects of political Romania, the author argues for not forgetting to take into account the informal, actor-related factors. The nature of the Romanian political parties and party system seems to hinder the finding of a consensus needed to exit the self-imposed blockade. More specifically, it is the Democratic Party (PD) that is the key to understanding the recent developments. The Government of April the third has yet to prove its efficiency.

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Current models of embryological development focus on intracellular processes such as gene expression and protein networks, rather than on the complex relationship between subcellular processes and the collective cellular organization these processes support. We have explored this collective behavior in the context of neocortical development, by modeling the expansion of a small number of progenitor cells into a laminated cortex with layer and cell type specific projections. The developmental process is steered by a formal language analogous to genomic instructions, and takes place in a physically realistic three-dimensional environment. A common genome inserted into individual cells control their individual behaviors, and thereby gives rise to collective developmental sequences in a biologically plausible manner. The simulation begins with a single progenitor cell containing the artificial genome. This progenitor then gives rise through a lineage of offspring to distinct populations of neuronal precursors that migrate to form the cortical laminae. The precursors differentiate by extending dendrites and axons, which reproduce the experimentally determined branching patterns of a number of different neuronal cell types observed in the cat visual cortex. This result is the first comprehensive demonstration of the principles of self-construction whereby the cortical architecture develops. In addition, our model makes several testable predictions concerning cell migration and branching mechanisms.