A bounded growth population subjected to emigrations due to population pressure

1981 ◽  
Vol 18 (3) ◽  
pp. 571-582 ◽  
Author(s):  
A. C. Trajstman
Keyword(s):  
Size Distribution ◽  
Population Level ◽  
Population Pressure ◽  
Population Increase ◽  
Time To Extinction ◽  
Mean Time To Extinction ◽  
The Mean ◽  
The Times ◽  
Negative Exponential ◽  
Mean Time

A model is presented for a bounded growth population subjected to random-sized emigrations that occur due to population pressure.The deterministic growth component examined in detail is defined by a Prendiville process. Results are obtained for the times between emigration events and for the population increase between emigrations. Some information is obtained about the mean time to extinction and also for the mean population level when the emigration-size distribution is negative exponential.

A bounded growth population subjected to emigrations due to population pressure

1981 ◽  
Vol 18 (03) ◽  
pp. 571-582 ◽  
Author(s):  
A. C. Trajstman
Keyword(s):  
Size Distribution ◽  
Population Level ◽  
Population Pressure ◽  
Population Increase ◽  
Time To Extinction ◽  
Mean Time To Extinction ◽  
The Mean ◽  
The Times ◽  
Negative Exponential ◽  
Mean Time

A model is presented for a bounded growth population subjected to random-sized emigrations that occur due to population pressure. The deterministic growth component examined in detail is defined by a Prendiville process. Results are obtained for the times between emigration events and for the population increase between emigrations. Some information is obtained about the mean time to extinction and also for the mean population level when the emigration-size distribution is negative exponential.

scholarly journals Growth of Integral Transforms and Extinction in Critical Galton-Watson Processes

2008 ◽  
Vol 45 (2) ◽  
pp. 472-480
Author(s):  
Daniel Tokarev
Keyword(s):  
Generating Function ◽  
Regular Variation ◽  
Probability Generating Function ◽  
Integral Transforms ◽  
Partial Sums ◽  
Finite Variance ◽  
Time To Extinction ◽  
Mean Time To Extinction ◽  
The Mean ◽  
Mean Time

The mean time to extinction of a critical Galton-Watson process with initial population size k is shown to be asymptotically equivalent to two integral transforms: one involving the kth iterate of the probability generating function and one involving the generating function itself. Relating the growth of these transforms to the regular variation of their arguments, immediately connects statements involving the regular variation of the probability generating function, its iterates at 0, the quasistationary measures, their partial sums, and the limiting distribution of the time to extinction. In the critical case of finite variance we also give the growth of the mean time to extinction, conditioned on extinction occurring by time n.

scholarly journals Growth of Integral Transforms and Extinction in Critical Galton-Watson Processes

2008 ◽  
Vol 45 (02) ◽  
pp. 472-480
Author(s):  
Daniel Tokarev
Keyword(s):  
Generating Function ◽  
Regular Variation ◽  
Probability Generating Function ◽  
Integral Transforms ◽  
Partial Sums ◽  
Finite Variance ◽  
Time To Extinction ◽  
Mean Time To Extinction ◽  
The Mean ◽  
Mean Time

The mean time to extinction of a critical Galton-Watson process with initial population size k is shown to be asymptotically equivalent to two integral transforms: one involving the kth iterate of the probability generating function and one involving the generating function itself. Relating the growth of these transforms to the regular variation of their arguments, immediately connects statements involving the regular variation of the probability generating function, its iterates at 0, the quasistationary measures, their partial sums, and the limiting distribution of the time to extinction. In the critical case of finite variance we also give the growth of the mean time to extinction, conditioned on extinction occurring by time n.

On the Extinction of the S–I–S stochastic logistic epidemic

1989 ◽  
Vol 26 (04) ◽  
pp. 685-694
Author(s):  
Richard J. Kryscio ◽  
Claude Lefèvre
Keyword(s):  
Chemical Reactions ◽  
Logistic Model ◽  
Diffusion Processes ◽  
Birth And Death Processes ◽  
Time To Extinction ◽  
Stochastic Logistic Model ◽  
Mean Time To Extinction ◽  
The Mean ◽  
Mean Time ◽  
Quasi Stationary Distribution

We obtain an approximation to the mean time to extinction and to the quasi-stationary distribution for the standard S–I–S epidemic model introduced by Weiss and Dishon (1971). These results are a combination and extension of the results of Norden (1982) for the stochastic logistic model, Oppenheim et al. (1977) for a model on chemical reactions, Cavender (1978) for the birth-and-death processes and Bartholomew (1976) for social diffusion processes.

On the Extinction of the S–I–S stochastic logistic epidemic

1989 ◽  
Vol 26 (4) ◽  
pp. 685-694 ◽  
Author(s):  
Richard J. Kryscio ◽  
Claude Lefèvre
Keyword(s):  
Chemical Reactions ◽  
Logistic Model ◽  
Diffusion Processes ◽  
Birth And Death Processes ◽  
Time To Extinction ◽  
Stochastic Logistic Model ◽  
Mean Time To Extinction ◽  
The Mean ◽  
Mean Time ◽  
Quasi Stationary Distribution

We obtain an approximation to the mean time to extinction and to the quasi-stationary distribution for the standard S–I–S epidemic model introduced by Weiss and Dishon (1971). These results are a combination and extension of the results of Norden (1982) for the stochastic logistic model, Oppenheim et al. (1977) for a model on chemical reactions, Cavender (1978) for the birth-and-death processes and Bartholomew (1976) for social diffusion processes.

Development of a commercial price schedule for producers and processors of lambs

1989 ◽  
Vol 29 (1) ◽  
pp. 23 ◽  
Author(s):  
DL Hopkins
Keyword(s):  
Multiple Regression ◽  
Carcass Weight ◽  
Commercial Application ◽  
Commercial Development ◽  
Time And Motion ◽  
Motion Study ◽  
The Mean ◽  
Fat Score ◽  
The Times ◽  
Mean Time

Equations were developed to predict the weight of trimmed retail (bone-in) cuts, trim, fat and bone from 321 lamb carcasses, ranging in carcass weight from 4.8 to 26.8 kg and in fat depth at the GR site (12th rib) from 1 to 31 mm. For commercial application, the equations were developed using a multiple regression program with the predictors carcass weight and GR. All equations explained a large amount of the variation in component weights (r2 = 0.76-0.99). A time and motion study using 172 carcasses showed that the times required to butcher carcasses of low fat (score 1 and 2) were similar. Likewise the mean time taken to butcher score 3 carcasses was similar to that of score 1 carcasses. However, it took significantly longer (P<0.05) to butcher score 3 carcasses than score 2 carcasses, and score 4 and 5 carcasses than score 3 carcasses. In addition, the mean times taken to butcher score 4 and 5 carcasses were significantly different (P< 0.05). By using multiple regression analysis it was shown that carcass weight, fatscore, their interaction and the butcher all significantly affected the butchering time. The findings of this work are discussed as they apply to the commercial development of price schedules and show that, when based on yield, lean heavy carcasses are more profitable for processing.

scholarly journals Controlled thawing of foods

2000 ◽  
Vol 18 (No. 5) ◽  
pp. 194-200 ◽  
Author(s):  
K. Hoke ◽  
L. Klíma ◽  
R. Grée ◽  
M. Houška
Keyword(s):  
Power Level ◽  
Point Of View ◽  
Hot Water ◽  
Similar Process ◽  
Hot Air ◽  
Air Temperatures ◽  
The Mean ◽  
Level 1 ◽  
The Times ◽  
Mean Time

The various ways of thawing of model food made for comparison of these processes from point of view of duration. The experiments were conducted under condition that the surface temperature of the thawed food did not overcome 15°C. Shortest mean time of thawing was achieved for vacuum-steam thawing. Regarding to the regime chosen the time of thawing varied between 18.4–29 min. The similar process of vacuum thawing with steam generated from hot water placed below the food was also successful. For this process the mean time of thawing was predicted between 30.5 and 35 min. If the starting temperature of the water was below the boiling point at vacuum level in the chamber the time of thawing was much longer (about 49 min). For hot air thawing we have tested two regimes with temperature of air 50 and 70°C. For both air temperatures the times of thawing were similar being 52.1 and 53.6 min, respectively. Microwave thawing was depending on the power of microwave oven. The time of thawing was achieved 28.9 min at power level 1, at power level “thawing” the process duration was 34.4 min.

scholarly journals Evaluating an icon of population persistence: the Devil's Hole pupfish

2014 ◽  
Vol 281 (1794) ◽  
pp. 20141648 ◽  
Author(s):  
J. Michael Reed ◽  
Craig A. Stockwell
Keyword(s):  
Count Data ◽  
Small Populations ◽  
Vulnerable Species ◽  
Human Intervention ◽  
Microsatellite Data ◽  
Time To Extinction ◽  
Credible Intervals ◽  
Mean Time To Extinction ◽  
Iconic Status ◽  
Mean Time

The Devil's Hole pupfish Cyprinodon diabolis has iconic status among conservation biologists because it is one of the World's most vulnerable species. Furthermore, C. diabolis is the most widely cited example of a persistent, small, isolated vertebrate population; a chronic exception to the rule that small populations do not persist long in isolation. It is widely asserted that this species has persisted in small numbers (less than 400 adults) for 10 000–20 000 years, but this assertion has never been evaluated. Here, we analyse the time series of count data for this species, and we estimate time to coalescence from microsatellite data to evaluate this hypothesis. We conclude that mean time to extinction is approximately 360–2900 years (median 410–1800), with less than a 2.1% probability of persisting 10 000 years. Median times to coalescence varied from 217 to 2530 years, but all five approximations had wide credible intervals. Our analyses suggest that Devil's Hole pupfish colonized this pool well after the Pleistocene Lakes receded, probably within the last few hundred to few thousand years; this could have occurred through human intervention.

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