Identification Of Critical Components Research Articles

Nuclear RNA export pathways.

One of the most profound differences between prokaryotes and eukaryotes is that only the latter segregate RNA synthesis and protein synthesis into distinct cellular compartments, i.e., into the nucleus and cytoplasm, respectively. This segregation offers opportunities for the regulation of both gene expression and RNA posttranscriptional processing that are not available to prokaryotes. However, it also means that eukaryotic cells must continuously transport large numbers of macromolecules between the nucleus and the cytoplasm in order that these can fulfill their appointed role in the life of the cell. In this review, I will describe the mechanisms used by the cell to move different classes of cellular RNA from their nuclear site of synthesis to the cytoplasm, where the majority then participate in the process of protein synthesis. While my primary focus will be on the insights that have been gleaned from the study of nuclear RNA export in vertebrate cells, I will also refer to studies with the yeast Saccharomyces cerevisiae which, because of its genetic malleability, has proven to be a valuable system for the identification of critical components of the nucleocytoplasmic transport machinery. More comprehensive overviews of nucleocytoplasmic transport, particularly of protein import, are provided by several excellent recent reviews in this area (21, 42, 50, 70).

Animal population dynamics: Identification of critical components

There is a growing interest in the use of population dynamics models in environmental risk assessment and the promulgation of environmental regulatory policies. Unfortunately, because of species and areal differences in the physical and biotic influences on population dynamics, such models must almost inevitably be both complex and species- or site-specific. Given the emormous variety of species and sites of potential concern, this fact presents a problem; it simply is not possible to construct models for all species and circumstances. Therefore, it is useful, before building predictive population models, to discover what input parameters are of critical importance to the desired output. This information should enable the construction of simpler and more generalizable models. As a first step, it is useful to consider population models as composed to two, partly separable classes, one comprising the purely mechanical descriptors of dynamics from given demographic parameter values, and the other describing the modulation of the demographic parameters by environmental factors (changes in physical environment, species interactions, pathogens, xenobiotic chemicals). This division permits sensitivity analyses to be run on the first of these classes, providing guidance for subsequent model simplification. We here apply such a sensitivity analysis to network models of mammalian and avian population dynamics.

Some considerations on reliability theory and its applications

Abstract In this paper we discuss some main topics within reliability theory and its applications. These include for example, modelling of systems of dependent components, identification of critical components, modelling of repairable systems, and the use of multistate models. The starting point for the discussion is Bergman's review paper on reliability theory and its application.

RELVEC — a tool for control system reliability analysis

This article will present a computerized reliability analysis tool for large control systems. It will also show a new dynamic representation of system structure. It enables us to model the physical system only once for any number of control tasks. The algorithm for computing minimal cut sets for the control tasks has been developed and automated. The result is RELVEC, an interactive computer program that performs reliability/availability calculation, sensitivity analysis and critical component identification. It can handle two repair policies and common mode failures. Reconfiquring of the physical system or the control tasks is simple. RELVEC is becoming an everyday tool in control system reliability analysis at VTT.