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Simple Mathematical Models (simple + mathematical_models)
Selected AbstractsImplications of a simple mathematical model to cancer cell population dynamicsCELL PROLIFERATION, Issue 1 2006A. L. Garner Many potential treatments preferentially interact with cells at certain stages of the cell cycle by either selective killing or halting the cell cycle, such as intense, nanosecond-duration pulsed electric fields (nsPEFs). Simple mathematical models of unfed cancer cell populations at the plateau of their growth characteristics may estimate the long-term consequences of these treatments on proliferating and quiescent cell populations. Applying such a model with no transition from the quiescent to proliferating state shows that it is possible for the proliferating cell population to fall below 1 if the quiescent cell population obtains a sufficient competitive advantage with respect to nutrient consumption and/or survival rate. Introducing small, realistic transition rates did not appreciably alter short-term or long-term population behaviour, indicating that the predicted small cell population behaviour (< 1 cell) is not an artefact of the simpler model. Experimental observations of nsPEF-induced effects on the cell cycle suggest that such a model may serve as a first step in assessing the viability of a given cancer treatment in vitro prior to clinical application. [source] Pre- and post-test mathematical modelling of a plan-asymmetric reinforced concrete frame building,EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 11 2006Peter Fajfar Abstract Pre- and post-test analyses of the structural response of a three-storey asymmetric reinforced concrete frame building were performed, aimed at supporting test preparation and performance as well as studying mathematical modelling. The building was designed for gravity loads only. Full-scale pseudo-dynamic tests were performed in the ELSA laboratory in Ispra. In the paper the results of initial parametric studies, of the blind pre-test predictions, and of the post-test analysis are summarized. In all studies a simple mathematical model, with one-component member models with concentrated plasticity was employed. The pre-test analyses were performed using the CANNY program. After the test results became available, the mathematical model was improved using an approach based on a displacement-controlled analysis. Basically, the same mathematical model was used as in pre-test analyses, except that the values of some of the parameters were changed. The OpenSees program was employed. Fair agreement between the test and numerical results was obtained. The results prove that relatively simple mathematical models are able to adequately simulate the detailed seismic response of reinforced concrete frame structures to a known ground motion, provided that the input parameters are properly determined. Copyright © 2006 John Wiley & Sons, Ltd. [source] REPRESSION OF COMPETITION AND THE EVOLUTION OF COOPERATIONEVOLUTION, Issue 4 2003Steven A. Frank Abstract Repression of competition within groups joins kin selection as the second major force in the history of life shaping the evolution of cooperation. When opportunities for competition against neighbors are limited within groups, individuals can increase their own success only by enhancing the efficiency and productivity of their group. Thus, characters that repress competition within groups promote cooperation and enhance group success. Leigh first expressed this idea in the context of fair meiosis, in which each chromosome has an equal chance of transmission via gametes. Randomized success means that each part of the genome can increase its own success only by enhancing the total number of progeny and thus increasing the success of the group. Alexander used this insight about repression of competition in fair meiosis to develop his theories for the evolution of human sociality. Alexander argued that human social structures spread when they repress competition within groups and promote successful group-against-group competition. Buss introduced a new example with his suggestion that metazoan success depended on repression of competition between cellular lineages. Maynard Smith synthesized different lines of thought on repression of competition. In this paper, I develop simple mathematical models to illustrate the main processes by which repression of competition evolves. With the concepts made clear, I then explain the history of the idea. I finish by summarizing many new developments in this subject and the most promising lines for future study. [source] MODELING DIMENSIONAL SHRINKAGE OF SHAPED FOODS IN FLUIDIZED BED DRYINGJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2005WIJITHA SENADEERA ABSTRACT Three particular geometrical shapes of parallelepiped, cylinder and sphere were selected from cut beans (length : diameter = 1:1, 2:1, 3:1), potatoes (aspect ratio = 1:1, 2:1, 3:1) and peas, respectively. The dimensional shrinkage behavior was studied in a batch fluidized bed at three drying temperatures of 30, 40 and 50C. Relative humidity of hot air was kept at 15%. Dimensional shrinkage was plotted using a nondimensional moisture ratio and the shrinkage behavior of the selected foods was modeled with simple mathematical models. [source] | ||||||||||