Heterogeneity and the modelling of bacterial spore death: the case of continuously decreasing death rate

1977 ◽  
Vol 23 (11) ◽  
pp. 1501-1507 ◽  
Author(s):  
Ken Sharpe ◽  
Roger M. Bektash
Keyword(s):  
Heat Resistance ◽  
Death Rate ◽  
Bacterial Spore ◽  
Bacterial Spores ◽  
Heating Process ◽  
Published Data ◽  
Model Based

Models for the inactivation of bacterial spores for the case of continuously decreasing death rate are reviewed and extended to show that it is not possible to distinguish between one particular model based upon the innate heterogeneity of the population and that based upon the acquisition of heat resistance during the heating process. Two innate heterogeneity models have been fitted to published data.

Death rates of bacterial spores: mathematical models

1976 ◽  
Vol 22 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Youn W. Han ◽  
Hwe Ik Zhang ◽  
John M. Krochta
Keyword(s):  
Heat Resistance ◽  
Mathematical Models ◽  
Bacterial Spores ◽  
Heating Process ◽  
Death Rates ◽  
Spore Population ◽  
Survivor Curve

The concave survivor curves produced as a result of spore heterogeneity were analyzed to determine whether they were caused by innate characteristics of the spores or by the acquisition of heat resistance during the heating process. Mathematical models developed for the two hypotheses revealed that the concave survivor curve (on semi-log paper) caused by innate heterogeneity is parabolic and that caused by acquired heat resistance is exponential. The mathematical models were applied to several published survivor curves of different organisms, and heat resistance parameters and the cause of curvilinearity were determined. For the cases studied, the cause of curvilinearity appears to be acquisition of heat resistance rather than innate heterogeneity of spore population.

The regulation of Ostertagia ostertagi populations in calves: the effect of past and current experience of infection on proportional establishment and parasite survival

Parasitology ◽  
1987 ◽  
Vol 95 (2) ◽  
pp. 363-372 ◽  
Author(s):  
B. T. Grenfell ◽  
G. Smith ◽  
R. M. Anderson
Keyword(s):  
Death Rate ◽  
Published Data ◽  
Cumulative Number ◽  
Intensity Of Infection ◽  
Decay Function ◽  
Ostertagia Ostertagi ◽  
Parasite Survival ◽  
Parasitic Phase ◽  
Current Experience

SUMMARYA mathematical model of the parasitic phase of the life-cycle of Ostertagia ostertagi in calves is described. The model is used in the re-analysis of previously published data from a long-term trickle infection experiment in which groups of calves were infected daily with graded doses of 3rd-stage (L3) larvae. The results of the analysis are consistent with the hypothesis that the observed changes in the intensity of infection in the calves were the result of a decline in the proportional establishment of ingested L3 larvae, and a rise in the death rate of the 5th-stage worms as the duration of exposure to infection increased. The proportion of ingested L3 larvae that become established in the mucosa can be described as an exponential decay function of the duration of the infection. Within the range of trickle intensities investigated, the function appears to vary independently of the level of exposure to infection. In contrast, the rate of mortality of the 5th-stage worms appears to be an increasing linear function of the total cumulative number of 3rd-stage larvae administered.

Death rates of bacterial spores: nonlinear survivor curves

1975 ◽  
Vol 21 (10) ◽  
pp. 1464-1467 ◽  
Author(s):  
Youn W. Han
Keyword(s):  
Heat Resistance ◽  
Bacillus Cereus ◽  
Saline Solution ◽  
Physiological Saline ◽  
Bacterial Spores ◽  
Death Rates ◽  
Physiological Saline Solution ◽  
Spore Population

Nonlinear survivor curves were obtained when spores of Bacillus cereus were heated in physiological saline solution. Curvilinear survivor curves did not appear to be caused by experimental artifacts but by the heterogeneity of spore population with regard to heat resistance.

Foraging ranges of penguins

Polar Record ◽  
1989 ◽  
Vol 25 (155) ◽  
pp. 303-308 ◽  
Author(s):  
Rory P. Wilson ◽  
Ken A. Nagy ◽  
Bryan S. Obst
Keyword(s):  
Simple Model ◽  
Range Limits ◽  
Published Data ◽  
Pygoscelis Adeliae ◽  
Model Based ◽  
Foraging Ranges

abstractSpeed/distance meters were deployed on adeliée, gentoo and chinstrap penguinsPygoscelis adeliae, P. papua and P. antarctica, breeding near Anvers Island, Antarctica. Underwater speeds and distances travelled were interspecifically very similar (means of ca. 7–8 km h-1and 15–45 km, respectively). These results are compared with published data on penguin behaviour at sea obtained by using identical methodology. A simple model, based on penguin activity at sea data, is developed to derive range limits for penguins. Derived range limits are substantially lower than previous estimates but accord well with distributional data obtained by transects.

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