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Exponential Growth Rate (exponential + growth_rate)
Selected AbstractsDEFINED ORDER OF EVOLUTIONARY ADAPTATIONS: EXPERIMENTAL EVIDENCEEVOLUTION, Issue 7 2008Erez Oxman Organisms often adapt to new conditions by means of beneficial mutations that become fixed in the population. Often, full adaptation requires several different mutations in the same cell, each of which may affect a different aspect of the behavior. Can one predict order in which these mutations become fixed? To address this, we experimentally studied evolution of Escherichia coli in a growth medium in which the effects of different adaptations can be easily classified as affecting growth rate or the lag-phase duration. We find that adaptations are fixed in a defined and reproducible order: first reduction of lag phase, and then an increase of the exponential growth rate. A population genetics theory explains this order, and suggests growth conditions in which the order of adaptations is reversed. We experimentally find this order reversal under the predicted conditions. This study supports a view in which the evolutionary path to adaptation in a new environment can be captured by theory and experiment. [source] Expansion and Validation of a Predictive Model for the Growth of Bacillus Stearothermophilus in Military RationsJOURNAL OF FOOD SCIENCE, Issue 5 2002T.M. Ng ABSTRACT: Predictive models for the exponential growth rate (EGR) and germination, outgrowth, and lag times (GOL) of Bacillus stearothermophilus previously developed in our laboratory were expanded to include higher salt (1.5%) formulations. The expanded models were validated in 7 military meals-ready-to-eat incubated at temperatures from 45 °C to 60 °C, and tryptic soy broth incubated from 37.5 °C to 70 °C. The 95% prediction intervals for EGR were fail-safe in all the military rations tested. The 95% prediction intervals for GOL were failsafe in 5 of the 7 rations. The TSB results illustrate the dangers of using empirical models to predict microbial behavior outside the range of conditions under which the models were developed. [source] Effect of temperature on epidemiological parameters of Puccinia lagenophoraePLANT PATHOLOGY, Issue 3 2001R. W. Kolnaar The effect of temperature on latent period and aeciospore production of Puccinia lagenophorae on Senecio vulgaris was determined in small-scale experiments under controlled conditions. A clear effect of temperature on latent period was demonstrated. Latent period decreased exponentially with increasing temperature. Both total aeciospore production and net reproductive number increased linearly with increasing temperature in a range from 10 to 22°C. The three parameters were incorporated in models to determine the effect of temperature on epidemic development. The present study suggests an increase in the exponential growth rate, r, and the velocity of focus expansion, V, with temperature. This increase in epidemic development was caused mainly by the effect of temperature on latent period and on net reproductive number. The effect of temperature on the sporulation curve appeared to be less important. [source] Stability of Linear Parameter Varying and Linear Switching SystemsPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003Fabian Wirth We consider stability of families of linear time-varying systems, that are determined by a set of time-varying parameters which adhere to certain rules. The conditions are general enough to encompass on the one hand stability questions for systems that are frequently called linear parameter varying systems in the literature and on the other hand also linear switching systems, in which parameter variations are allowed to have discontinuities. Combinations of these two sets of assumptions are also possible within the framework studied here. Under the assumption of irreducibility of the sets of system matrices, we show how to construct parameter dependent Lyapunov functions for the systems under consideration that exactly characterize the exponential growth rate. It is clear that such Lyapunov functions do not exist in general. But every system of our class can be reduced to a finite number of subsystems for which irreducibility holds. [source] Effective condition number of Trefftz methods for biharmonic equations with crack singularitiesNUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 2 2009Zi-Cai Li Abstract The paper presents the new stability analysis for the collocation Trefftz method (CTM) for biharmonic equations, based on the new effective condition number Cond_eff. The Trefftz method is a special spectral method with the particular solutions as admissible functions, and it has been widely used in engineering. Three crack models in Li et al. (Eng. Anal. Boundary Elements 2004; 28:79,96; Trefftz and Collocation Methods. WIT Publishers: Southampton, Boston, 2008) are considered, and the bounds of Cond_eff and the traditional condition number Cond are derived, to give the polynomial and the exponential growth rates, respectively. The stability analysis explains well the numerical experiments. Hence, the new Cond_eff is more advantageous than Cond. Besides since the bounds of Cond_eff and Cond involve the estimation of the minimal singular value ,min of the discrete matrix F, and since the estimation of ,min is challenging and difficult, the proof for lower bounds of ,min in this paper is important and intriguing. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||